ECS System Architecture Blueprint (SAB)¶

Enterprise Architecture Objectives¶

The Enterprise Architecture (EA) perspective provides the structural foundation for the External Configuration System (ECS) as a multi-tenant, SaaS-grade platform. While the Vision Document articulated why ECS matters and the BRD captured what it must deliver, the EA blueprint defines how ECS must be architected to achieve scalability, compliance, and ecosystem readiness.

🎯 Role of the Enterprise Architect for ECS¶

Bridge Business and Technology: Translate ECS business drivers (multi-tenant configuration, SaaS monetization, governance) into actionable architectural principles and systems.
Define Enterprise-Level Standards: Apply ConnectSoft’s EA principles (Clean Architecture, Event-Driven, Observability-First, Cloud-Native, Security-First).
Enable Ecosystem Fit: Ensure ECS integrates seamlessly with ConnectSoft SaaS products, libraries, agents, and marketplace.
Governance & Compliance Steward: Guarantee that ECS meets SOC2, GDPR, HIPAA compliance while maintaining tenant autonomy.
Future-Proofing: Provide a blueprint that scales from MVP to ecosystem-wide adoption and federation.

🏆 Key Architecture Drivers¶

1. Scalability¶

ECS must scale across thousands of tenants and millions of config entities.
Support horizontal elasticity (auto-scaling, sharding, caching).
Ensure global distribution with active-active replication.

2. Compliance¶

Full alignment with SOC2, GDPR, ISO27001, and other standards required by enterprise tenants.
Data residency control (EU/US/APAC).
Immutable audit trails and long-term retention policies.

3. SaaS Readiness¶

Delivered as a first-class SaaS product in the ConnectSoft catalog.
Multi-tenant, edition-aware, environment-scoped from inception.
Seamless integration with ConnectSoft Marketplace for billing and tenant lifecycle.
Fit into ecosystem-wide observability, identity, and governance frameworks.

📐 EA Objective Diagram¶

mindmap
  root((ECS EA Objectives))
    Role of EA
      Bridge Business & Tech
      Define Standards
      Enable Ecosystem Fit
      Governance & Compliance
      Future-Proofing
    Key Drivers
      Scalability
      Compliance
      SaaS Readiness

Hold "Alt" / "Option" to enable pan & zoom

📌 Enterprise Architect Notes¶

ECS is not just a configuration utility but a strategic SaaS backbone.
EA ensures ECS is modular, extensible, and interoperable across ConnectSoft and external ecosystems.
Every architectural decision (services, APIs, events, storage, governance) must trace back to these EA objectives.

✅ With objectives defined, the EA blueprint now has a north star: ECS must scale securely, comply rigorously, and serve as a SaaS-ready foundation across ConnectSoft.

Business–Technology Alignment¶

The External Configuration System (ECS) exists at the intersection of business strategy and technical execution. From the Enterprise Architect’s perspective, the primary responsibility is to ensure that the business objectives outlined in the Vision Document and BRD translate into architectural drivers, KPIs, and design choices that guarantee long-term success.

🎯 Alignment with Business Objectives¶

Centralize Configuration Management → ECS architecture must provide a single source of truth with strong consistency guarantees.
Enable Tenant & Edition-Aware Configs → Requires bounded contexts and policy-driven override layers.
Ensure Compliance & Auditability → Implies immutable audit trails, encryption by default, and regulatory-ready data pipelines.
Improve Agility & Time-to-Market → Calls for real-time event-driven refresh, SDKs, and integration with CI/CD.
Deliver as SaaS → Architecture must be multi-tenant by design, with billing hooks and consumption metering.

📊 Translating Business KPIs to Architecture KPIs¶

Business KPI	Corresponding Architecture KPI
Tenant Adoption Rate	ECS can support 10k+ tenants with strong isolation guarantees.
Feature Delivery Speed	Config changes propagate in <5 seconds (p95).
Compliance Readiness	Audit logs immutable and exportable within 24h for compliance teams.
ARR from ECS Subscriptions	ECS supports tiered pricing metrics (config objects, refresh events).
Tenant Satisfaction (NPS)	SDKs require <10 lines of integration; portal usability rated ≥80%.

🔗 EA Role in Business–Tech Alignment¶

Traceability: Every ECS feature traces back to a business objective.
Decision Governance: EA ensures technical decisions (storage, event bus, APIs) reinforce business goals.
Feedback Loops: Observability data feeds business insights (usage, adoption, churn).
Ecosystem Synergy: ECS doesn’t live alone—its value grows as more ConnectSoft SaaS products adopt it.

📐 Alignment Diagram¶

flowchart TD
    BO[Business Objectives] --> EA[Enterprise Architect]
    EA --> AD[Architecture Drivers]
    AD --> SA[SaaS Architecture Blueprint]
    SA --> KPI[Business & Technical KPIs Met]

Hold "Alt" / "Option" to enable pan & zoom

📌 Enterprise Architect Notes¶

ECS architecture must speak the language of the business.
Metrics must be observable from day one—no hidden “black box” components.
Business–technology alignment is not a one-off; it’s a continuous governance loop.

Context & Scope Definition¶

The External Configuration System (ECS) operates as a cross-cutting SaaS backbone in the ConnectSoft ecosystem. Its architecture must define clear system boundaries, integration points, and scope of responsibility to prevent overlap with other services (e.g., Identity, Secrets Vault, Observability).

🌍 ECS in the ConnectSoft Ecosystem¶

Core Role: ECS is the centralized source of truth for configuration across ConnectSoft SaaS products, microservices, and agents.
Consumers: Identity, Billing, API Gateway, AI Factory Agents, DevOps pipelines, and tenant applications.
Differentiation: ECS is not a secrets store (Key Vault) or feature flag platform by itself, but it can integrate with both.
Marketplace Integration: ECS is sold and managed as a standalone SaaS product via the ConnectSoft Marketplace.

✅ In-Scope¶

Configuration Entities: CRUD, versioning, rollback, inheritance (global → edition → tenant → environment).
Config Distribution: Real-time refresh events, SDK integration, caching.
Multi-Tenant & Edition Awareness: Strong tenant isolation, edition-based rules, RBAC.
Audit & Compliance: Immutable audit logs, GDPR/SOC2 readiness.
Self-Service Portal (Config Studio): UI for admins, PMs, and tenant users.
Integration Adapters: Out-of-the-box support for ConnectSoft SaaS, Azure AppConfig, AWS AppConfig.

🚫 Out-of-Scope¶

Secrets & Credential Management → handled by ConnectSoft Key Vault / Azure Key Vault / AWS Secrets Manager.
Workflow Engines → ECS will expose APIs/events but not orchestrate full workflows.
Heavy Analytics → ECS provides usage dashboards and adoption metrics, but deep BI belongs to ConnectSoft Analytics Services.
Feature Flag Management as Primary Product → ECS supports toggles but does not compete directly with LaunchDarkly or FeatureHub in v1.

📐 ECS Context Diagram¶

flowchart TD
    subgraph ECS [External Configuration System]
        A1[Config Store]
        A2[Event Bus]
        A3[Config Studio UI]
        A4[SDKs & APIs]
    end

    subgraph ConnectSoft [ConnectSoft Ecosystem]
        B1[Identity Service]
        B2[Billing & Marketplace]
        B3[AI Factory Agents]
        B4[Observability Platform]
        B5[API Gateway & Microservices]
    end

    subgraph External [External Platforms]
        C1[Azure AppConfig]
        C2[AWS AppConfig]
        C3[3rd Party SaaS Apps]
    end

    B1 --> ECS
    B2 --> ECS
    B3 --> ECS
    B4 --> ECS
    B5 --> ECS

    ECS --> C1
    ECS --> C2
    ECS --> C3

Hold "Alt" / "Option" to enable pan & zoom

📌 Enterprise Architect Notes¶

ECS must have sharp boundaries: configs only, not secrets, not workflows.
Positioning ECS as a source of truth avoids duplication of config logic across services.
Out-of-scope items are critical guardrails—they ensure ECS remains lightweight, scalable, and focused.

Architecture Principles¶

The External Configuration System (ECS) must be designed in accordance with ConnectSoft enterprise architecture standards, ensuring it is scalable, secure, observable, and ecosystem-aligned. These principles serve as the foundation for all downstream design and implementation decisions.

🧩 Core Principles¶

Clean Architecture & DDD
- ECS services are layered (Domain, Application, Infrastructure, Interface).
- Bounded contexts: Global Config, Edition Config, Tenant Config, Policy.
- Entities and aggregates represent config objects, editions, tenants, users, and audit events.
Event-Driven by Default
- Every change (create, update, rollback) raises CloudEvents-compliant domain events.
- Downstream systems (DevOps, QA, Observability) consume ECS events asynchronously.
- Refresh signals propagate in near real-time (<5s).
Observability-First
- OpenTelemetry traces for every API/SDK call.
- Metrics exposed for tenant activity, SLA adherence, config drift.
- Full auditability baked into system flows.
Cloud-Native & Resilient
- Stateless services, deployed on AKS or equivalent.
- Elastic scaling (HPA/KEDA) based on load.
- Active-active multi-region replication with <30s drift.
Security-First, Compliance-Ready
- Zero-trust design: authenticate every call, authorize per scope.
- Tenant isolation enforced at DB and service layers.
- Compliance baked in: SOC2, GDPR, HIPAA-ready.
Multi-Tenant & SaaS-Aware
- ECS is multi-tenant by design—no “single-tenant hacks”.
- Edition-awareness allows product tiering via configs.
- Integrates with ConnectSoft Marketplace billing for monetization.
Extensible & Pluggable
- Config providers (SQL, Redis, CosmosDB) must be pluggable.
- Integration adapters for Azure AppConfig, AWS AppConfig.
- Modular SDKs, lightweight and extensible.

📐 Principle Map¶

mindmap
  root((ECS Architecture Principles))
    Clean Architecture
      Domain-Driven
      Bounded Contexts
    Event-Driven
      CloudEvents
      Refresh <5s
    Observability
      OTEL
      Metrics & Logs
    Cloud-Native
      Elastic Scaling
      Multi-Region
    Security & Compliance
      Zero-Trust
      SOC2/GDPR
    Multi-Tenant
      Tenant Isolation
      Edition-Aware
    Extensible
      Pluggable Providers
      Adapters (Azure/AWS)

Hold "Alt" / "Option" to enable pan & zoom

📌 Enterprise Architect Notes¶

These principles are non-negotiable guardrails—they shape every downstream design.
ECS must be lean enough for developer adoption but robust enough for enterprise trust.
Adherence to ConnectSoft architectural standards guarantees ECS integrates smoothly into the ecosystem.

High‑Level System Blueprint¶

This blueprint defines the core ECS services, boundaries, and integrations, aligning with ConnectSoft Clean Architecture + DDD and the Microservice Template (Domain, Application, Infrastructure, Interface). It emphasizes multi‑tenant SaaS, event‑driven refresh, and enterprise‑grade governance.

Core Components & Boundaries¶

flowchart TB
  %% Boundaries
  subgraph Edge["Edge - Experience Layer"]
    UI[🖥 Config Studio - SPA+API]
    SDK[📦 SDKs .NET,JS,Mobile]
  end

  subgraph Core["Core Domain Services"]
    API[⚙️ Config API Service]
    RES[🧩 Effective Config Resolver]
    POL[🛡 Policy & Entitlements Engine]
    AUD[📝 Audit & Compliance Service]
    EVT[📣 Event Publisher - Notifier]
    SNAP[📄 Snapshot & Export Service]
  end

  subgraph Data["State & Caching"]
    DB[(Config DB - SQL,Cockroach)]
    CACHE[(Redis - Hot Cache)]
    WORM[(WORM Storage - Audit Log)]
    BLOB[(Blob Storage - Snapshots)]
  end

  subgraph Integrations["Ecosystem & External"]
    IAM[🔑 Identity - OIDC,OAuth2]
    O11Y[📊 Observability - OTEL,Prom,Grafana]
    BILL[💳 Marketplace & Billing]
    BUS[(Event Bus - Kafka,Service Bus)]
    ACFG[☁ Azure AppConfig Adapter]
    WCFG[☁ AWS AppConfig Adapter]
    GW[🚪 API Gateway]
  end

  %% Flows
  UI-->API
  SDK-->API
  API-->RES
  API-->POL
  RES-->CACHE
  RES-->DB
  POL-->DB
  API-->AUD
  API-->SNAP
  API--changes-->EVT
  EVT-->BUS
  AUD-->WORM
  SNAP-->BLOB

  GW-->API
  IAM-->GW
  BUS-->SDK
  BUS-->Edge
  O11Y<-->API
  O11Y<-->RES
  O11Y<-->EVT
  BILL<-->API
  API<-->ACFG
  API<-->WCFG

Hold "Alt" / "Option" to enable pan & zoom

Highlights

Edge exposes Config Studio (self‑service portal) and SDKs for apps/services.
Core hosts domain services: Config API, Resolver, Policy, Audit, Event Publisher, Snapshot.
Data separates operational config, hot cache, immutable audit, and export artifacts.
Integrations cover Identity, Observability, Billing, Event Bus, and cloud adapters.

Runtime Flows (Read Path & Change Propagation)¶

sequenceDiagram
  participant Admin as Tenant Admin / PM
  participant UI as Config Studio
  participant API as Config API
  participant POL as Policy Engine
  participant DB as Config DB
  participant AUD as Audit Svc
  participant EVT as Event Publisher
  participant BUS as Event Bus
  participant APP as SaaS App + SDK

  Admin->>UI: Edit/Save Config
  UI->>API: PUT /configs/{id} (payload+scope)
  API->>POL: Validate policy/overrides
  POL-->>API: OK / Violations
  API->>DB: Persist new version
  API->>AUD: Write audit record (who/what/why/diff)
  API->>EVT: Publish ConfigChanged(domain event)
  EVT->>BUS: CloudEvents (tenant/edition/env scoped)
  BUS-->>APP: Notify subscribers (refresh token)
  APP->>APP: SDK reloads in‑memory cache (idempotent)

Hold "Alt" / "Option" to enable pan & zoom

Read Path (steady state) SDK → Cache first → fallback to Resolver+DB → Policy enforcement → ETag/Version returned → OTEL trace emitted.

Microservices & Responsibilities¶

Service	Responsibility	Key Interfaces
Config API	CRUD, versioning, diff, rollback; scope & query	REST/gRPC, OpenAPI, OTel, OAuth2
Effective Config Resolver	Computes final config: global→edition→tenant→env	Internal gRPC; cache integration; ETag
Policy & Entitlements Engine	Edition rules, override guardrails, schema validation	gRPC lib; policy DSL; admin APIs
Audit & Compliance	Append‑only audit, export, compliance views	Write‑behind to WORM; SIEM exports
Event Publisher / Notifier	Emits CloudEvents; fan‑out to bus & websockets	Kafka/Service Bus; WebSocket hub
Snapshot & Export	Point‑in‑time snapshots; bulk import/export	Async jobs; Blob storage
Config Studio	RBAC UI, editors, diff, preview, rollout workflows	SPA (SPA→API); OIDC; feature flags
Adapters (Azure/AWS)	Sync to external AppConfig; federation	Async sync jobs; conflict policy

Template Alignment: Each service adheres to ConnectSoft Microservice Template layering (Domain, Application, Infra, Interface) and uses shared ConnectSoft Libraries for messaging, persistence, telemetry, security.

Data & Storage View¶

Config DB (SQL/Cockroach): multi‑tenant row‑level security; versioned aggregates.
Redis Cache: effective config snapshots keyed by {tenant}:{env}:{app}:{hash} with TTL + stampede protection.
WORM Audit Store: immutable, append‑only; 7‑year retention; SIEM export.
Blob Storage: snapshots, imports/exports, large JSON payloads.

External & Ecosystem Integrations¶

Identity: OIDC/OAuth2; RBAC scopes config.read/write/admin.
Event Bus: Kafka/Azure Service Bus; CloudEvents schema; DLQs for failures.
Observability: OpenTelemetry traces, Prometheus metrics, Grafana dashboards.
Marketplace/Billing: usage metering (config objects, refresh events) for tier enforcement.
Cloud Adapters: Azure AppConfig/AWS AppConfig sync (ECS as source of truth; optional bidirectional ingest).

Trust Zones & Network¶

Public Zone: API Gateway, Config Studio SPA, read‑only config endpoints.
Service Zone: Core services (API, Resolver, Policy, Audit, Events).
Data Zone: DB, Redis, WORM, Blob (private subnets, restricted SGs).
Messaging Zone: Event bus cluster with TLS + authN.
Zero‑Trust: mTLS between services; per‑tenant scoping claims; policy at gateway + service.

Deployment Topology (Cloud‑Native)¶

AKS (or equivalent): stateless pods; HPA/KEDA for elastic scale.
Multi‑Region Active‑Active: read locality, write quorum, ≤30s cross‑region event drift.
Blue/Green & Canary: traffic splitting at gateway for API and UI; staged config rollouts managed by Event Publisher.
Config Snapshots: enable offline‑first consumption during transient outages.

Non‑Functional Guardrails (at Blueprint Level)¶

Latency: p95 read < 50 ms (cache hit), p95 refresh propagation < 5 s.
SLA: 99.95% per region; RPO ≤ 0; RTO < 1 min (failover).
Security: TLS 1.3, AES‑256 at rest, tenant isolation, signed refresh messages.
Compliance: SOC2/ISO27001 controls mapped to services; GDPR data residency via regional deployments.

Enterprise Architect Notes

Keep policy enforcement centralized to prevent config sprawl and drift.
Treat effective config as a first‑class computed view with caching and strong invariants.
Design events CloudEvents‑first to simplify ecosystem choreography and analytics.

Domain Decomposition & Bounded Contexts (DDD)¶

This section carves the External Configuration System (ECS) into autonomous, business-aligned bounded contexts. Each context owns its ubiquitous language, aggregates, policies, data, and APIs. Interactions are event-driven and contracted to prevent leakage and coupling.

Context Map (Strategic Design)¶

flowchart LR
  subgraph Authoring["Config Authoring"]
    A1[Schema Catalog]
    A2[Drafts & Reviews]
    A3[Versioning]
  end

  subgraph Serving["Config Serving & Resolution"]
    S1[Read API]
    S2[Resolution Engine]
    S3[Cache]
  end

  subgraph Tenancy["Tenant & Edition Management"]
    T1[Tenant Registry]
    T2[Edition/Plan Rules]
    T3[Env Topology]
  end

  subgraph Policy["Policy & Governance"]
    G1[Policy Registry]
    G2[Guardrails]
    G3[Approvals]
  end

  subgraph Refresh["Refresh & Distribution"]
    R1[Refresh Bus]
    R2[SDK Signals]
    R3[Edge Caches]
  end

  subgraph Integrations["Provider Integrations"]
    P1[Azure AppConfig]
    P2[AWS AppConfig]
    P3[SQL/Redis/EF]
  end

  subgraph Portal["Config Studio (UI)"]
    U1[Workspaces]
    U2[Wizards]
    U3[Diff & Rollback]
  end

  subgraph Observability["Observability & Audit"]
    O1[Audit Trail]
    O2[OTEL Metrics]
    O3[SLO Analyzer]
  end

  subgraph Billing["Billing & Subscriptions"]
    B1[Plans & Quotas]
    B2[Usage Metering]
    B3[Invoicing Signals]
  end

  %% Relationships
  Authoring -- emits --> Refresh
  Authoring -- publishes --> Serving
  Authoring -- consults --> Policy
  Serving -- consumes --> Tenancy
  Serving -- emits --> Observability
  Refresh -- pushes --> SDKs
  Integrations <---> Serving
  Portal <---> Authoring
  Portal --> Policy
  Billing -- reads --> Observability

Hold "Alt" / "Option" to enable pan & zoom

Vision Architect Notes: We split change (Authoring) from use (Serving) to isolate write-optimised workflows from read-optimised, low‑latency delivery. Cross‑cutting Tenancy, Policy, Observability, and Billing act as platforms, not dependencies.

Contexts → Capabilities → Primary Aggregates¶

Context	Core Capabilities	Primary Aggregates / Entities
Config Authoring	Schema management, typed keys, drafts, reviews, semantic diff, versioning, rollback	`ConfigSchema`, `ConfigKey`, `ConfigValueVersion`, `ChangeSet`, `Release`
Config Serving & Resolution	Low‑latency reads, hierarchical resolution (global→tenant→edition→environment→app), evaluation of rules	`ResolvedSnapshot`, `ResolutionRule`, `ResolutionPlan`, `CacheEntry`
Tenant & Edition Management	Tenant isolation, plan/edition rules, environment topology, namespaces	`Tenant`, `Edition`, `Environment`, `Namespace`
Policy & Governance	Guardrails, SoD approvals, validation gates, PII/secret classification	`Policy`, `ApprovalFlow`, `Guardrail`, `SecretClass`
Refresh & Distribution	Eventing, fan‑out to SDKs, ETags, lease-based invalidation, edge caches	`RefreshEvent`, `DistributionChannel`, `LeaseToken`
Provider Integrations	Import/export connectors (Azure/AWS/SQL/Redis/EF), sync jobs, ACL	`ProviderConnection`, `SyncJob`, `Mapping`
Config Studio (UI)	Workspaces, wizards, safe editors, preview-as-tenant/edition, diffs	`Workspace`, `EditorSession`, `PreviewContext`
Observability & Audit	Audit trail, metrics, SLOs, anomaly detection, change impact	`AuditRecord`, `MetricStream`, `Anomaly`, `SLO`
Billing & Subscriptions	Plans, quotas (objects, refresh calls), metering, invoicing signals	`Subscription`, `Quota`, `UsageRecord`, `InvoiceSignal`

Vision Architect Notes: Aggregates are narrowly scoped. For example, ConfigValueVersion is immutable; Release groups versions and becomes the unit of promotion/canary/rollback.

Ubiquitous Language (Core Terms)¶

Config Key – A typed, namespaced identifier (e.g., payments.retry.maxAttempts:int).
Version – Immutable value snapshot tied to key + metadata (author, reason, checksum).
Release – A group of versions promoted together; carries rollout rules and audit.
Resolution – Process that computes the effective value given tenant/edition/env/app.
Override – A higher-specificity value replacing a broader one along the resolution chain.
Guardrail – A policy that rejects unsafe values before publish (e.g., PII in plaintext).
Refresh Event – A signed, tenant-scoped signal for SDKs/caches to re-hydrate.
Snapshot – Read-optimized bundle used by SDKs; addresses consistency & latency.

Vision Architect Notes: The language deliberately separates authoring vocabulary (draft, review, release) from runtime vocabulary (resolution, snapshot, refresh).

Aggregate Design (Tactical DDD)¶

Config Authoring¶

ConfigSchema
- Invariants: stable type, constraints, classification (e.g., secret).
- Operations: add field, deprecate field (non-breaking), evolve minor/major.
ConfigValueVersion
- Invariants: immutable payload; must pass Policy + Schema.
- Events: ConfigValueVersionCreated, ValidationFailed.
Release
- Invariants: contains a consistent set of ConfigValueVersion ids; idempotent promote.
- Events: ReleasePromoted, ReleaseRolledBack.

Serving & Resolution¶

ResolutionRule (value object) – precedence matrix: global < tenant < edition < env < app.
ResolvedSnapshot (aggregate) – materialized view for hot reads; events: SnapshotBuilt, SnapshotExpired.

Tenancy & Editions¶

Tenant, Edition, Environment – own isolation boundaries and quotas; events: TenantCreated, EditionUpgraded, EnvironmentLinked.

Policy & Governance¶

Policy – composable constraints (regex, ranges, secret-only storage, approval state).
ApprovalFlow – SoD stages with required roles; events: ApprovalRequested, ApprovalGranted/Rejected.

Refresh & Distribution¶

RefreshEvent – signed, verifiable, replay-safe; LeaseToken – prevents storm refresh.
Events: RefreshEmitted, CacheInvalidated.

Integrations¶

ProviderConnection, SyncJob, Mapping – define external sync contracts; events: SyncStarted, SyncCompleted, SyncFailed.

Observability & Audit¶

AuditRecord – append-only; events: ChangeAudited, PolicyViolationRecorded, SLOBreached.

Billing¶

UsageRecord – meter units: keys, versions, snapshots, refresh calls; events: UsageCaptured, QuotaBreached.

Vision Architect Notes: Where read/write contention is high (Authoring vs Serving), we favor CQRS: commands mutate Authoring aggregates; queries read Snapshots built by Serving.

Domain Event Catalog (Inter‑Context Contracts)¶

Event	Producer Context	Consumer Contexts	Purpose
`ConfigValueVersionCreated`	Authoring	Policy, Observability	Validate & audit new version
`ReleasePromoted`	Authoring	Serving, Refresh, Observability, Billing	Build snapshots, emit refresh, meter usage
`PolicyViolationRecorded`	Policy	Observability, Portal	Alert and block promotion
`SnapshotBuilt`	Serving	Refresh, Observability	Notify caches & SDKs of new snapshot
`RefreshEmitted`	Refresh	SDKs/Edges, Observability, Billing	Fan‑out refresh; meter signals
`SyncCompleted`	Integrations	Authoring, Observability	Reconcile external providers
`TenantCreated`	Tenancy	Authoring, Serving, Billing	Initialize namespaces/quotas
`SLOBreached`	Observability	Policy, Portal	Enforce throttles/guardrails
`QuotaBreached`	Billing	Portal, Policy	Grace handling, block promotions

Vision Architect Notes: Events are semantic, not CRUD. They carry tenant, edition, environment, namespace, and traceId for end-to-end correlation.

Context Integration Styles¶

Authoring → Serving: Outbox + Event Bus; Serving builds ResolvedSnapshot asynchronously.
Serving → SDKs: Pull + Push hybrid (ETag-based GET + subscribed RefreshEvent).
Policy in Authoring: In‑process checks + policy service for heavy/rich validations.
Provider Integrations: Anti‑Corruption Layer (ACL) masks external data shapes.
Observability: OTEL spans on commands/queries; audit on immutability edges.

Vision Architect Notes: Prefer event-driven propagation over synchronous coupling. Only the read path exposes synchronous APIs to SDKs.

Resolution Precedence Model¶

graph TB
  Global --> Tenant
  Tenant --> Edition
  Edition --> Environment
  Environment --> Application
  Application --> ResolvedValue["Resolved Value"]

Hold "Alt" / "Option" to enable pan & zoom

Rule: the most specific wins; explicit null can unset at a higher scope when allowed.
Conflict Handling: deterministic order + policy guardrails + linting during Release.

Vision Architect Notes: Precedence is immutable and published as part of the public contract; SDKs can locally simulate resolution for preview.

Data Ownership & Isolation¶

Each context owns its write model.
Authoring: append‑only value history; Serving: derived snapshots (rebuildable).
Tenant/Edition as partition keys across stores and topics.
Secrets never egress plaintext; classified values stored via secret providers.

Vision Architect Notes: Snapshots are ephemeral—reproducible from history. This enables disaster recovery and time-travel rollback.

Example Command & Event (Intent‑first)¶

# Command (Authoring)
PromoteRelease:
  tenantId: "acme"
  namespace: "payments"
  releaseId: "rel-2025-08-001"
  approvals: ["sec-approver-1", "owner-2"]
  traceId: "t-9f3e..."

# Emitted Events
- ReleasePromoted { tenantId, namespace, releaseId, checksum, traceId }
- SnapshotBuilt   { tenantId, namespace, snapshotId, etag, traceId }
- RefreshEmitted  { tenantId, namespace, channels: ["sdk","edge"], etag, traceId }
- UsageCaptured   { tenantId, metric: "refresh.signals", count: 124, traceId }

Vision Architect Notes: Commands never include raw values—only references to immutable versions to preserve auditability and minimize payload size.

Anti‑Corruption Layers (Integrations)¶

Azure/AWS AppConfig, SQL/Redis/EF adapters translate:
- External schemas ⇄ ConfigSchema
- External keys ⇄ namespaced ConfigKey
- External change notifications ⇄ internal ReleasePromoted/RefreshEmitted

Vision Architect Notes: Keep external provider semantics at the boundary. Inside ECS, everything is normalized to ECS language and events.

Guardrails (Cross‑Cutting)¶

Policy checks on every write: schema conformity, secret classification, range/rules, SoD approvals.
Snapshot linter prior to publish: unresolved references, circular overrides, missing required keys.
SLOs on Serving: p95 read latency, snapshot build time, refresh fan‑out time.

Vision Architect Notes: Guardrails are part of the domain, not just middleware. Failed guardrails emit policy events and block state transitions.

Outcome¶

This decomposition gives ECS:

Clear ownership per context
Low-latency reads decoupled from safe authoring
Event contracts for propagation and ecosystem integration
Tenant-first isolation and audit‑ready immutability

It is now straightforward to allocate teams/agents, scale components independently, and evolve ECS without destabilizing the whole.

Service Decomposition & Responsibilities¶

Scope: external, multi-tenant ECS (External Configuration System) SaaS. Services are cleanly separated by bounded context, event-driven, observable, and cloud-native. Each service below is independently deployable and replaceable via ConnectSoft templates.

Service Inventory (by responsibility)¶

Service	Core Responsibility	Key Inputs	Key Outputs	Primary Events (emit/consume)	Owning Context
Config Registry API	CRUD for config objects (namespaces, keys, JSON docs), versioning, labels	Auth’d requests, policy decisions	Versioned config snapshots, diff views, access decisions	Emits `ConfigCreated/Updated/Deleted`, `VersionTagged`; Consumes `PolicyDecisionEvaluated`	Config Management
Policy & Governance	RBAC/ABAC, schema rules, PII tags, change windows, approval workflows	Policy definitions, tenant/role attributes	Permit/Deny decisions, policy violations, approval tasks	Emits `PolicyDecisionEvaluated`, `ChangeApprovalRequired`, `PolicyViolationDetected`	Governance
Tenant & Edition Manager	Tenant onboarding, edition/plan entitlements, environment overlays	Billing plan, marketplace purchase, admin inputs	Edition matrices, entitlement tokens	Emits `EditionEntitlementsChanged`, `TenantProvisioned`; Consumes `SubscriptionUpdated`	Tenancy
Refresh Dispatcher	Real-time invalidation & cache refresh fanout	Change events from Config Registry	Bus notifications to SDKs/agents	Emits `ConfigRefreshRequested`, `RefreshBroadcasted`	Delivery
Provider Adapter Hub	Pluggable storage/providers (SQL, Redis, Blob, AppConfig, Consul)	Provider configs, secrets	Provider-specific read/write operations	Emits `ProviderSyncCompleted`; Consumes `ProviderSyncRequested`	Integration
Config Studio (UI)	Self-service portal for tenants, editors, approvals	User sessions, API data	UX workflows, audit trails	Emits `UiChangeProposed`, `UiChangeApproved`	Experience
Audit & Observability	Append-only audit, metrics, traces, anomaly detection	Platform telemetry, change events	Audit records, risk alerts	Emits `AnomalyDetected`, `AuditRecordAppended`; Consumes all	Compliance
SDK Distribution	Package + endpoint distribution (.NET, JS, mobile), config resolution logic	Build artifacts, version manifests	SDK feeds, resolver policies	Emits `SdkReleasePublished`	Developer Experience
Admin & Backoffice	Super-tenant admin, catalog, couponing, feature flags for ECS itself	Admin commands	Catalog updates, global toggles	Emits `EcsFeatureToggleChanged`	Platform
Billing & Plans	Metering (reads, refreshes, config objects), invoicing signals	Usage counters, tenant plan	Billing events, quotes	Emits `UsageReported`, `BillingExportReady`; Consumes `TenantProvisioned`	Monetization
Gateway & Edge Cache	High-throughput reads with edge caching & ETag	Client SDK read requests	Cached responses, 304 hints	Emits `EdgeCacheInvalidated`; Consumes `RefreshBroadcasted`	Delivery
Rollout Orchestrator	Safe rollout strategies (ring, canary, time windows)	Change sets, policy window	Rollout steps, pause/resume	Emits `RolloutStepStarted/Completed`, `RolloutPaused`	Delivery
Import/Export & Federation	Bulk import, export, cross-region/cross-cloud sync	Files, remote endpoints	Federation jobs, diffs	Emits `FederationSyncCompleted`; Consumes `FederationSyncRequested`	Integration
Secrets Broker	Indirection to KMS/Vault; never stores secrets as data	Secret refs, access tokens	Short-lived secret handles	Emits `SecretAccessed`; Consumes `PolicyDecisionEvaluated`	Security

Vision Architect Notes Services are grouped to minimize chatty coupling: Write path (Registry→Policy→Rollout→Refresh) and Read path (SDK/Gateway→Provider Hub/Cache). “Audit & Observability” consumes all change and access events for compliance.

Responsibility Breakdown (concise RASCI)¶

R = Responsible, A = Accountable, S = Supports, C = Consulted, I = Informed

Capability	Registry API	Policy & Gov	Tenant/Edition	Refresh Dispatcher	Gateway/Edge	Audit/Obs	Rollout	Provider Hub
CRUD config objects	R/A	C	I	I	I	I	I	S
Versioning & rollback	R/A	C	I	I	I	S	C	S
Approval workflows	S	R/A	C	I	I	S	S	I
Entitlement checks	C	S	R/A	I	I	I	I	I
Real-time refresh	I	C	I	R/A	S	I	S	S
Edge caching	I	I	I	S	R/A	I	I	I
Rollout strategies	C	S	I	S	I	I	R/A	I
Cross-provider sync	C	I	I	I	I	I	I	R/A

Change Flows (Write Path)¶

sequenceDiagram
  participant User/SDK
  participant Studio
  participant Registry
  participant Policy
  participant Rollout
  participant Refresh
  participant Audit

  Studio->>Registry: Propose change (draft)
  Registry->>Policy: Evaluate policy (schema, RBAC, windows)
  Policy-->>Registry: Permit/Deny (+approvals)
  Registry->>Rollout: Create ChangeSet (rings/canary)
  Rollout->>Registry: Apply step (ring N)
  Registry->>Refresh: Emit ConfigUpdated (+version)
  Refresh->>User/SDK: Broadcast Refresh (topic/tenant/key)
  Registry->>Audit: AppendAudit(ChangeApplied)
  Policy->>Audit: AppendAudit(Decision)
  Rollout->>Audit: AppendAudit(RolloutStep)

Hold "Alt" / "Option" to enable pan & zoom

Vision Architect Notes Policy decisions happen before version finalization to ensure immutable history reflects governed state. Rollout produces repeatable, observable steps with pause/abort via policy outcomes.

Read Flows (Hot Path / 99^th percentile)¶

flowchart LR
  ClientSDK -->|GetConfig-namespace,key,labels| Edge[Gateway & Edge Cache]
  Edge -->|CacheHit| ClientSDK
  Edge -->|CacheMiss| ProviderHub
  ProviderHub --> Primary[Primary Provider -SQL/EF/AppConfig]
  ProviderHub --> Secondary[Secondary/Failover -Redis/Blob]
  Primary --> Edge
  Edge --> ClientSDK
  Refresh[Refresh Dispatcher] -->|Invalidate| Edge

Hold "Alt" / "Option" to enable pan & zoom

Vision Architect Notes Reads prefer Edge Cache with ETag and stale-while-revalidate. Provider Hub abstracts backends, enabling per-tenant storage strategies (e.g., premium tenants on AppConfig).

Event Contract Highlights (selected)¶

ConfigCreated/Updated/Deleted { tenantId, namespace, key, version, actor, labels[], traceId }
PolicyDecisionEvaluated { decision, reasons[], policyIds[], actor, traceId }
ConfigRefreshRequested { tenantId, namespace, key, targetAudiences[], ttl }
RolloutStepStarted/Completed { changeSetId, ring, affectedTenants, metrics }
AuditRecordAppended { category, subjectType, subjectId, actor, outcome }
EditionEntitlementsChanged { tenantId, edition, features[] }

Vision Architect Notes All contracts are tenant-scoped and carry traceId for cross-service correlation. Emitted events are append-only; corrections are modeled as compensating events.

Data Ownership & Boundaries¶

Config Registry API owns: ConfigObject, ConfigVersion, Namespace, LabelSet
Policy & Governance owns: Policy, Rule, Approval, Window, Exception
Tenant & Edition owns: Tenant, EditionPlan, Entitlement
Refresh Dispatcher owns: RefreshJob, Subscription
Audit & Observability owns: AuditRecord, MetricSeries, AnomalySignal
Provider Hub owns adapter configurations; does not own config domain data

Vision Architect Notes Ownership ensures single-writer principles and clean anti-corruption between Registry and external providers.

Failure & Resiliency Responsibilities¶

Failure Domain	Primary Handler	Strategy
Provider outage	Provider Hub	Circuit-breaker, fallback to secondary provider, read-through cache
Refresh fanout spikes	Refresh Dispatcher	Backpressure, batching, topic partitioning, retry with DLQ
Policy service latency	Registry API	Cached last-known-permit for read-only ops, deny-by-default on mutations
Edge cache stampede	Gateway	Request coalescing, collapsed forwarding
Audit sink pressure	Audit & Obs	Async buffering, lossless backends for regulated tiers

Vision Architect Notes All critical paths include idempotency keys and exactly-once semantics where required (e.g., version commit).

Service-to-Template Mapping (ConnectSoft assets)¶

Service	Template Basis	Notable Libraries
Registry API	Microservice Template (.NET + Clean + DDD)	OpenAPI, NHibernate/EF, FluentValidation
Policy & Governance	Microservice Template + Rules Engine ext	Policy DSL, JSON Schema, OPA-compatible adapters
Tenant & Edition	Microservice Template	Identity/OIDC, Plan matrix library
Refresh Dispatcher	Worker/Queue Template	MassTransit, Azure Service Bus
Provider Hub	Adapter Service Template	Provider SDKs (AWS/Azure/Consul), Resilience library
Gateway & Edge	YARP/API Gateway Template	ETag middleware, Cache abstractions
Audit & Obs	Microservice Template + OTEL	Serilog, OTEL exporters, risk scoring
Rollout Orchestrator	Orchestrator/Coordinator Template	FSM engine, time windows
SDK Distribution	Static/site + Package Publisher	NuGet/NPM publisher agents
Import/Export & Federation	Worker + API	CSV/JSON pipelines, diff engine
Secrets Broker	Minimal API + Vault Adapter	Key Vault/Secrets Manager clients

Vision Architect Notes Each service is generated from opinionated templates to enforce layering, observability, and security. Adapters live in separate libraries to keep domains clean.

Responsibility Guardrails (policy snippets)¶

guardrails:
  registry:
    writesRequire: [policy.permit, approval.completed?]
    emits: [ConfigCreated, ConfigUpdated, VersionTagged]
  gateway:
    allowWrite: false
    cache:
      mode: stale-while-revalidate
      etag: strong
  refresh:
    fanout:
      maxBatch: 1000
      retryPolicy: expo_5x
  audit:
    piiRedaction: enforced
    retention:
      default: 365d
      enterprise: 2555d

Vision Architect Notes Guardrails are enforced by CI policy tests and runtime validators; violations block release to regulated tiers.

Open Questions to Close (for subsequent cycles)¶

Should Rollout Orchestrator own freeze windows or remain in Policy & Governance?
Do we require per-key encryption-at-rest beyond provider guarantees (KMS-bound envelopes)?
What’s the default SLA for refresh fanout by tier (e.g., <500ms P95 enterprise)?

Vision Architect Notes These decisions affect service accountability boundaries and SLAs. Recommend capturing as ADRs before detailed design.

Data Architecture & Lifecycle¶

The External Configuration System (ECS) is data-centric: all services depend on versioned, immutable config entities. A robust data architecture ensures consistency, tenant isolation, compliance, and recoverability.

Entity-Relationship Model (ERD)¶

erDiagram
    TENANT ||--o{ EDITION : has
    TENANT ||--o{ ENVIRONMENT : owns
    TENANT ||--o{ NAMESPACE : scopes

    NAMESPACE ||--o{ CONFIG_KEY : contains
    CONFIG_KEY ||--o{ CONFIG_VERSION : evolves
    CONFIG_VERSION ||--o{ RELEASE : grouped_into
    RELEASE ||--o{ SNAPSHOT : materializes

    CONFIG_VERSION ||--o{ POLICY_RESULT : validated_by
    POLICY_RESULT }o--|| POLICY : references

    RELEASE ||--o{ REFRESH_EVENT : triggers
    SNAPSHOT ||--o{ CACHE_ENTRY : cached_as

    TENANT ||--o{ USAGE_RECORD : billed_by
    USAGE_RECORD }o--|| SUBSCRIPTION : allocated_to

    TENANT ||--o{ AUDIT_RECORD : audited_by

Hold "Alt" / "Option" to enable pan & zoom

Entities

Tenant / Edition / Environment / Namespace → multi-tenant isolation & scoping.
ConfigKey / ConfigVersion / Release / Snapshot → lifecycle of configuration.
Policy / PolicyResult → validation & guardrails.
RefreshEvent / CacheEntry → distribution layer.
AuditRecord / UsageRecord → compliance & billing hooks.

Data Lineage & Lifecycle¶

flowchart LR
  Draft[Draft Config] --> Valid[Validation & Policy]
  Valid -->|OK| Version[ConfigVersion (immutable)]
  Version --> Release[Release (grouped set)]
  Release --> Snapshot[Snapshot (Resolved per tenant/env/app)]
  Snapshot --> Refresh[RefreshEvent to SDKs/Edges]
  Snapshot --> Cache[Cached Entry in Redis/Edge]
  Version --> Archive[Archive / Cold Storage]

Hold "Alt" / "Option" to enable pan & zoom

Draft: transient, mutable, not visible to consumers.
Version: immutable, validated, signed; always reproducible.
Release: logical grouping of versions; unit of rollout, rollback.
Snapshot: resolved, tenant-specific materialization; hot cache entry.
Refresh Event: signals SDKs and caches.
Archive: long-term retention; WORM storage for compliance.

Retention & Compliance¶

Data Type	Retention	Storage Class	Notes
Config Versions	2 years (enterprise configurable)	SQL/Cockroach (primary)	Immutable history, required for rollback.
Releases	2 years	SQL/Cockroach	Linked to audit.
Snapshots	30–90 days	Redis / Blob	Rebuildable from versions.
Audit Records	7 years	WORM (immutable)	SOC2/GDPR/HIPAA compliance.
Usage Records	2 years	SQL/Blob	For billing reconciliation.
Policy Results	1 year	SQL	Validation history.
Refresh Events	7–30 days	Bus logs	Short-term replay for diagnostics.

Data Residency

Tenants mapped to regional clusters (EU, US, APAC).
Row-level security per tenant; strong isolation.
Audit & WORM stores replicated only within residency region.

Partitioning Strategy¶

Horizontal Partitioning:
- tenantId = partition key across all stores.
- environment and namespace secondary keys.
Database Sharding: CockroachDB multi-region sharding; resilience to node/region loss.
Cache Partitioning: Redis cluster partitioned by tenant:env:ns:app.
Event Bus Partitioning: by tenantId; ensures consumption fairness.

Data Flow Observability¶

All data operations traced with OTEL.
Change correlation: traceId included in ConfigVersion, Release, RefreshEvent.
Anomaly detection: drift detection between authoritative store vs provider adapters.

Enterprise Architect Notes¶

ECS data is immutable and append-only at its core; rollback is always reconstructive, never destructive.
Retention is tiered: hot (Redis/SQL), warm (Blob), cold (WORM archive).
Partitioning ensures scale-out and tenant fairness while preserving compliance.
ERD and lifecycle diagrams should be version-controlled alongside code and updated with every schema change.

Integration Architecture — External Configuration System (ECS)¶

How ECS connects with ConnectSoft services and external platforms, enabling secure, observable, multi-tenant configuration delivery across runtimes.

Integration Goals¶

Unified config plane for all ConnectSoft SaaS and customer apps (backend, frontend, mobile, agents).
Zero‑trust, tenant‑isolated access via OAuth2/OIDC and scoped API keys.
Event‑driven refresh across services, edges, and devices.
Pluggable providers (Azure/AWS/SQL/Redis/Files) behind a stable domain API.
Observability-first: every integration emits traces, logs, metrics, and audit events.

High-Level Integration Map¶

graph TB
  subgraph ConnectSoft Core
    IdP[Identity - OIDC]
    TenReg[Tenant Registry]
    Billing[Billing & Plans]
    Cat[Product Catalog]
    Obs[Observability Mesh - OTEL, Logs, Metrics]
    Bus[Event Bus - Service Bus/RabbitMQ]
    Mkpl[Marketplace]
  end

  subgraph ECS SaaS
    API[ECS Public API - REST/gRPC]
    Studio[ECS Config Studio - Admin UI]
    Gate[Policy & AuthZ]
    Proxy[Edge Proxy - CDN/PoP]
    Pub[Refresh Publisher]
    Prov[Provider Abstraction]
    CfgDB[(Config Store)]
    Cache[(Hot Cache)]
    Audit[(Audit & Versioning)]
  end

  subgraph External Runtimes
    SvcA[ConnectSoft Microservices]
    SvcB[3rd-Party Services]
    FE[Web/Mobile Apps]
    Agents[Agent Runtimes]
  end

  subgraph External Providers
    AzAppCfg[Azure App Configuration]
    AwsAppCfg[AWS AppConfig]
    Redis[Redis/Mem + Stream]
    Sql[SQL / CockroachDB]
    Consul[HashiCorp Consul]
    S3[S3/Blob - JSON Bundles]
  end

  IdP-->Gate
  TenReg-->Gate
  Billing-->Gate
  Cat-->Studio
  Mkpl-->API
  Obs<-->API
  Obs<-->Pub

  API-->Prov
  Studio-->API
  Gate-->API
  Prov-->CfgDB
  Prov-->Cache
  Prov-->Audit

  Prov<-->AzAppCfg
  Prov<-->AwsAppCfg
  Prov<-->Redis
  Prov<-->Sql
  Prov<-->Consul
  Prov<-->S3

  API-->Proxy
  Pub-->Bus
  Bus-->SvcA
  Proxy-->FE
  API-->SvcA
  API-->SvcB
  API-->Agents

Hold "Alt" / "Option" to enable pan & zoom

Key: ECS exposes a stable Public API, a Config Studio for admins, Provider Abstraction to external systems, and Refresh Publisher to broadcast change events over the platform bus.

Core Integration Patterns¶

1) Identity & Access (ConnectSoft IdP)¶

Protocol: OIDC/OAuth2 (client credentials for services, auth code + PKCE for humans).
Scopes (examples):
- ecs:read:{tenantId}
- ecs:write:{tenantId}
- ecs:admin:{tenantId}
Claims used: tenantId, edition, roles, subject, customerId.
Policy checks happen in Gate before every API operation; deny-by-default.

sequenceDiagram
  participant App as Microservice
  participant IdP as ConnectSoft IdP
  participant ECS as ECS API
  App->>IdP: Client Credentials (scope: ecs:read:tenant-123)
  IdP-->>App: Access Token (aud=ecs, tenantId=123)
  App->>ECS: GET /v1/config?env=prod (Bearer)
  ECS->>ECS: Policy check (tenantId match, scope)
  ECS-->>App: 200 + settings payload

Hold "Alt" / "Option" to enable pan & zoom

2) Tenant, Edition, and Billing Hooks¶

Tenant Registry: canonical authority for tenantId, status, regions. ECS reads and caches tenant metadata for policy decisions and routing (e.g., data residency).
Billing & Plans: usage metering signals from ECS (config objects, refresh events, deliveries) → Billing; plan checks at write/refresh time (throttle/limit).
Product Catalog: edition/features metadata → ECS edition overlays and visibility rules.

3) Event-Driven Refresh & Rollout¶

Trigger: ConfigVersionPublished (after commit/publish in Studio or API).
Propagation:
- Emit Ecs.ConfigChanged on Event Bus (tenant-scoped, env, keys fingerprint).
- Push Server‑Sent Events/WebSocket to long‑lived SDK clients (optional).
- Edge invalidation (CDN/Proxy) for static bundles.

flowchart LR
  Author[Config Author] -->|Publish| ECS_API
  ECS_API --> Version[Create Version + Sign]
  Version --> Audit
  Version --> Event[Ecs.ConfigChanged - Bus]
  Event --> R1[Microservices]
  Event --> R2[Mobile/Web SDKs]
  Event --> R3[Agent Runtimes]
  R1 -->|Pull/Delta| ECS_API
  R2 -->|SSE/WebSocket| ECS_API

Hold "Alt" / "Option" to enable pan & zoom

4) Provider Abstraction Layer¶

Goal: vendor‑neutral ECS API with adapters to popular backends.
Contract (conceptual):

providerContract:
  get(keys, context) -> ConfigSet
  put(changes, context) -> VersionId
  watch(channel, context) -> ChangeEvents
  capabilities: [atomicVersioning, hierarchicalKeys, targeting, driftDetect]

Built‑in adapters: SQL/CockroachDB, Redis (+streams), Azure App Configuration, AWS AppConfig, Consul, S3/Blob bundles.
Routing: per tenant/env policy selects adapter(s); supports dual‑write + cutover migrations.

5) Observability & Audit¶

All calls traced with OTEL: traceId, tenantId, edition, caller, keys.
Metrics: config_fetch_latency, config_bytes_delivered, refresh_events_total, cache_hit_ratio.
Audit log: append‑only store of changes, publisher identity, diff summary, policy outcomes.

Integration Interfaces¶

Public REST (selected)¶

GET   /v1/config?env=prod&keys=app:*,db:conn
POST  /v1/config/publish { draftId }
GET   /v1/config/versions?since=2025-08-01
GET   /v1/stream/changes?env=prod   (SSE)

Headers: Authorization: Bearer, X-Tenant-Id, X-Edition, X-Trace-Id.
Response includes: version, ttl, signature, hash, targetingRulesApplied.

gRPC (service excerpt)¶

service ConfigService {
  rpc GetConfig(GetConfigRequest) returns (GetConfigResponse);
  rpc Publish(PublishRequest) returns (PublishResponse);
  rpc WatchChanges(WatchRequest) returns (stream ChangeEvent);
}

Event Contracts¶

{
  "eventType": "Ecs.ConfigChanged",
  "version": "1.0",
  "tenantId": "tenant-123",
  "environment": "prod",
  "keys": ["app/*","features/*"],
  "publishedVersion": "v2025.08.24-14",
  "signature": "sig:v1:...",
  "traceId": "trace-abc"
}

SDK Integration (Runtime Clients)¶

Runtime	Mode	Refresh
.NET (Microsoft.Extensions.Configuration provider)	Pull + background refresh	SSE/Bus
Node/JS (Edge, SPA)	Signed bundle via CDN + delta fetch	SSE
Mobile (Xamarin/MAUI)	Offline cache + staged rollout	SSE
Python/Go agents	Simple REST + ETag/If-None-Match	Bus/SSE

Common features:

ETag/version pinning, staged rollout (percentage, audience rules).
Fallback chain: tenant:edition > tenant > global.
Local hot cache with TTL + signature verification.

External Platform Bridges¶

Azure App Configuration (Bridge)¶

Sync modes:
- Mirror: ECS ↔ Azure AppConfig bi‑directional keysync (namespaced).
- Read‑through: ECS queries Azure AppConfig when miss → caches result.
Auth: Managed Identity or Client Secret per tenant.
Events: Ecs.ConfigChanged → triggers AppConfig label update (optional).

AWS AppConfig (Bridge)¶

Publish: ECS publishes versioned JSON profile → AWS AppConfig environment.
Rollout: ECS can initiate or observe AWS AppConfig deployment strategies.
Back‑pressure: respect AWS throttles; batch updates by tenant/env.

Redis / Consul / SQL¶

Redis: hot path cache + pub/sub channel ecs:tenant:env for push signals.
Consul: K/V mapping; ACL token per tenant; watch for changes.
SQL/CockroachDB: canonical version store; optimistic concurrency; row‑level tenancy.

Network & Topology¶

graph LR
  Clients{{Apps, Services, Agents}} -- mTLS/HTTPS --> EdgeCDN
  EdgeCDN -- signed bundles/ETag --> APIGW[API Gateway]
  APIGW -- OIDC introspection --> IdP
  APIGW --> ECSAPI[ECS API Pods]
  ECSAPI --> ProvSvc[Provider Pods]
  ProvSvc --> Primary[(Primary Store)]
  ProvSvc --> Cache[(Redis)]
  ECSAPI --> Bus[(Event Bus)]
  ECSAPI --> Obs[(OTEL/Logs/Metrics)]

Hold "Alt" / "Option" to enable pan & zoom

Zero‑trust: mTLS between gateway and pods; per‑workload identities.
Regional shards for data residency; tenant‑to‑region mapping via Tenant Registry.
CDN for static config bundles (read‑only tenants; e.g., SPA/mobile).

Integration Matrix (Who Talks to Whom)¶

Integrator	Direction	Interface	Purpose
Tenant Registry → ECS	Pull	REST/gRPC	Resolve tenant/region/edition
Billing ↔ ECS	Both	Events + REST	Metering, plan enforcement
Marketplace ↔ ECS	Both	REST	Subscription lifecycle
Observability Mesh ↔ ECS	Both	OTEL, Logs, Metrics	Traces, metrics, audits
Event Bus ↔ ECS	Both	Pub/Sub	`Ecs.ConfigChanged` propagation
Azure/AWS/Consul/Redis/SQL ↔ ECS	Both	Provider Adapters	External configuration backends
Clients (SDKs) ↔ ECS	Both	REST/gRPC + SSE	Fetch + streaming refresh
Edge CDN/Proxy ↔ ECS	Both	Signed Bundles	Low-latency distribution

Reference Sequences¶

A) Safe Publish with Staged Rollout¶

sequenceDiagram
  participant Admin as Config Admin (Studio)
  participant ECS as ECS API
  participant Prov as Provider Adapter
  participant Audit as Audit/Version
  participant Bus as Event Bus
  participant Svc as Services/SDKs

  Admin->>ECS: Publish Draft #42 (tenant=123, env=prod, 10% rollout)
  ECS->>Prov: Commit as Version v2025.08.24-14
  Prov-->>ECS: OK + checksum
  ECS->>Audit: Append version + diff + signer
  ECS->>Bus: Ecs.ConfigChanged (target=10%)
  Svc-->>ECS: Fetch delta (If-None-Match: prev)
  ECS-->>Svc: 200 + new keys + version sig
  Note over Svc: SDKs apply rollout rules locally

Hold "Alt" / "Option" to enable pan & zoom

B) Drift Detection (External Provider)¶

sequenceDiagram
  participant ECS as ECS Drift Monitor
  participant Ext as External Provider (e.g., Consul)
  participant Audit as Audit Log
  ECS->>Ext: List namespace keys @ expected version
  Ext-->>ECS: Keys mismatch (manual change)
  ECS->>Audit: Record DriftDetected + details
  ECS->>Bus: Ecs.PolicyAlert (severity=warn)

Hold "Alt" / "Option" to enable pan & zoom

Data Contracts (Selected)¶

Config Payload (normalized)¶

{
  "tenantId": "tenant-123",
  "environment": "prod",
  "version": "v2025.08.24-14",
  "hash": "sha256:...",
  "issuedAt": "2025-08-24T08:21:12Z",
  "ttlSeconds": 3600,
  "items": {
    "app/theme": "dark",
    "db/conn": "@secret:kv://tenant-123/prod/db",
    "features/payments": true
  },
  "rules": [
    {"if": {"edition":"pro"}, "set": {"features/advancedDashboard": true}}
  ],
  "signature": "sig:v1:..."
}

Provider Adapter Registration¶

adapters:
  - name: azure-appconfig
    match: tenant.region == "eu" && env in ["prod","staging"]
    settings:
      connection: "msi:resource-id:/subs/.../appConfig"
  - name: sql-cockroach
    match: env == "dev"
    settings:
      connString: "Host=...;Database=ecs..."

Secrets: never stored inline; @secret: indirection only (Key Vault/Secrets Manager).
Signature: server‑side signing of payload + version; SDK verifies before apply.
RBAC: per‑tenant roles; admin/write separated from read/consume.
Rate limits: per client/tenant; backoff headers on limit exhaustion.
PII Governance: JSON schema lint blocks PII in config values unless policy:allow.

Failure Modes & Backoffs¶

Scenario	ECS Behavior
Provider unavailable	Serve from Cache/Edge; mark `stale=true`, short TTL
Event bus outage	SDKs poll on backoff; retry with jitter
Token expired	401 + `www-authenticate`; SDK rotates credentials
Signature mismatch	Reject apply; log `SecurityEvent` + quarantine

Deliverables for Engineering & Ops¶

API & gRPC proto packages (ConnectSoft.Ecs.Client for .NET, @connectsoft/ecs-sdk for JS).
Adapter SDK (IProviderAdapter) + ready adapters (Azure/AWS/SQL/Redis/Consul).
Helm charts/terraform/bicep for ECS multi‑region deployment.
Dashboards: fetch latency, refresh events, error rate, drift alerts.
Runbooks: cutover to new provider, bulk key migration, incident response.

Integration Readiness Checklist¶

IdP scopes & policies created; API gateway introspection enabled.
Tenant Registry sync job deployed; residency routing validated.
Billing meters receiving events; plan enforcement rules active.
Event topics provisioned: Ecs.ConfigChanged.*, Ecs.PolicyAlert.*.
Provider adapters configured per region/env; dual‑write tested.
OTEL exporters verified; dashboards populated.
SDKs integrated in sample microservice + SPA + agent runtime.
Edge/CDN bundle flow validated; ETag/signature round‑trip.

This section defines how ECS “plugs into” the ConnectSoft ecosystem and external config platforms while preserving tenant isolation, observability, and portability via a provider abstraction.

Event‑Driven Architecture Model¶

Design ECS as an event‑native system: all meaningful state changes emit events, and all consumers (SDKs, gateways, tenants, ConnectSoft services) react asynchronously. This enables safe propagation, auditability, and multi‑region rollout with strong tenant isolation.

Event Taxonomy¶

Domain	Event	Purpose	Key Producers	Key Consumers
Config Lifecycle	`ConfigSetCreated`	A new logical config set was created (name, scope)	Config Authoring API	Studio, Audit, Search Indexer
	`ConfigItemUpserted`	Add/update a key/value (with schema validation result)	Authoring API	Versioning Service, Cache, Audit
	`ConfigDraftValidated`	Draft passed schema & policy gates	Validation Service	Publisher, Studio
	`ConfigVersionPublished`	Version N becomes active in ENV/Edition/Tenant	Publisher	SDK Refresh Topic, CDN/Cache
	`ConfigVersionRolledBack`	Revert to known‑good version	Publisher, Ops	SDK Refresh Topic, Audit
Refresh & Distribution	`RefreshSignalRequested`	Caller requests push refresh	Publisher, Tenant Admin	Refresh Orchestrator
	`RefreshSignalDispatched`	Fan‑out refresh with etag/version targeting	Refresh Orchestrator	SDKs, Edge Cache
Governance	`PolicyViolationDetected`	PII/secret/constraint breach in draft	Validator	Studio, Audit, Security
	`AccessPolicyChanged`	RBAC change for config scopes	IAM/Policy Service	Authoring API, Audit
Topology & Tenancy	`TenantCreated` / `TenantSuspended`	Lifecycle changes impact config visibility	Tenant Service	Segmenter, Billing
	`EditionChanged`	Edition matrix update (lite/pro/ent)	Product Catalog	Resolver, Publisher
Schema	`SchemaChanged`	New schema or breaking/non‑breaking change	Schema Registry	Validator, Publisher
Ops & SRE	`HotfixWindowOpened`/`Closed`	Allow emergency publish bypassing some gates	Ops Console	Publisher, Audit

Event Envelope & Metadata (Standard)¶

All ECS events share a common envelope to guarantee traceability, multi‑tenant isolation, and ordering.

{
  "eventId": "01J7S4A2K9Z4X9",
  "eventType": "ConfigVersionPublished",
  "occurredAt": "2025-08-24T10:23:31Z",
  "specVersion": "ecs.events.v1",
  "tenant": {
    "tenantId": "t-92f",
    "edition": "enterprise",
    "environments": ["staging", "prod"]
  },
  "correlation": {
    "correlationId": "pub-6b8e",
    "causationId": "draft-1a2b"
  },
  "routing": {
    "partitionKey": "t-92f",
    "region": "westeurope",
    "orderingKey": "config:notification-service"
  },
  "security": {
    "sig": "JWS-compact",
    "mTLS": true
  },
  "payload": {
    "configSet": "notification-service",
    "version": 42,
    "etag": "W/\"42-0x8f9a\"",
    "scope": { "env": "prod", "edition": "enterprise" },
    "diffSummary": { "added": 3, "updated": 1, "removed": 0 }
  }
}

EA design notes

partitionKey=tenantId enforces isolation and improves throughput.
orderingKey=configSet guarantees per‑set ordering while allowing global concurrency.
Signed envelopes enable zero‑trust consumption across regions.

Core Event Schemas (Selected)¶

ConfigItemUpserted

{
  "payload": {
    "configSet": "payment-service",
    "key": "retryPolicy.maxAttempts",
    "value": 5,
    "dataType": "int",
    "validation": { "schemaId": "payment.v3", "status": "passed" },
    "versionPreview": 17
  }
}

ConfigVersionPublished

{
  "payload": {
    "configSet": "payment-service",
    "version": 18,
    "previousVersion": 17,
    "scope": { "env": "prod", "edition": "pro" },
    "semanticChange": "non-breaking"
  }
}

RefreshSignalDispatched

{
  "payload": {
    "targets": [
      { "appId": "svc:checkout", "env": "prod", "region": "westeurope" },
      { "appId": "svc:checkout", "env": "prod", "region": "eastus" }
    ],
    "config": { "set": "payment-service", "etag": "W/\"18-0xabcd\"" },
    "policy": { "maxSkewSeconds": 60, "graceful": true }
  }
}

Channels, Topics, and Routing¶

Channel	Semantics	Partitioning	Consumers
`ecs.config.lifecycle.v1`	Create/Upsert/Validate/Publish/Rollback	`tenantId`	Authoring UI, Studio, Audit, Search
`ecs.refresh.signals.v1`	High‑fan‑out refresh hints	`tenantId` + `configSet`	SDKs, Edge Cache
`ecs.governance.v1`	Policy & access changes	`tenantId`	Security, Audit
`ecs.schema.v1`	Schema/catalog updates	global	Validator, Generator
`ecs.ops.v1`	Ops windows & overrides	global	Publisher, Audit

EA design notes

Use Azure Service Bus topics for lifecycle/governance and Event Hubs or Kafka for high‑volume refresh signals (optional dual‑plane).
Edge caches subscribe to ecs.refresh.signals.v1 with per‑region filters.

Event Flows (Choreography)¶

A. Draft → Validate → Publish → Refresh¶

sequenceDiagram
  participant Author as Authoring UI
  participant API as Authoring API
  participant Val as Validator
  participant Pub as Publisher
  participant Bus as Event Bus
  participant SDK as App SDKs/Agents

  Author->>API: Upsert draft items
  API-->>Bus: ConfigItemUpserted
  Bus-->>Val: ConfigItemUpserted
  Val-->>Bus: ConfigDraftValidated(status=passed)
  Author->>API: Publish version
  API-->>Pub: publish(configSet, version)
  Pub-->>Bus: ConfigVersionPublished
  Pub-->>Bus: RefreshSignalRequested
  Bus-->>SDK: RefreshSignalDispatched (fan-out)
  SDK->>SDK: Conditional pull (If-None-Match: etag)

Hold "Alt" / "Option" to enable pan & zoom

EA design notes

Validation emits explicit events; Publisher refuses to publish without passed status for the same draft correlationId.
SDKs perform idempotent pulls keyed by etag.

B. Edition‑Aware Override Flow¶

flowchart LR
  A[EditionChanged] --> B[Resolver recomputes effective config]
  B --> C[ConfigVersionPublished - edition override]
  C --> D[RefreshSignalDispatched → Edition filter]

Hold "Alt" / "Option" to enable pan & zoom

EA design notes

The Resolver computes effective values via precedence: Tenant > Edition > Environment > Global.

Sagas (Orchestrated, Compensating Actions)¶

Publish‑to‑Production Saga (Multi‑Region)¶

stateDiagram-v2
  [*] --> StageRegions
  StageRegions --> Canary10 : publish vN (1 region)
  Canary10 --> Monitor : metrics/logs OK?
  Monitor --> Canary50 : yes
  Monitor --> Rollback : no
  Canary50 --> GlobalRollout
  GlobalRollout --> SealVersion : freeze vN
  SealVersion --> [*]
  Rollback --> SealPrev : revert to vN-1
  SealPrev --> [*]

Hold "Alt" / "Option" to enable pan & zoom

Steps

StageRegions: publish to staging per region → ConfigVersionPublished(staging)
Canary10/50: partial tenant cohort; emit RefreshSignalDispatched with target filters
Monitor: watch error rate/latency SLOs; if violated → RollbackRequested
GlobalRollout: fan‑out remaining regions/tenants
SealVersion: mark version immutable and seal audit record

EA design notes

Saga state persisted with transactional outbox; all transitions emit events to the bus.
Compensations are first‑class (ConfigVersionRolledBack with reasonCode).

Reliability & Ordering Patterns¶

At‑least‑once delivery with idempotent consumers (use (configSet, version, operation) as idempotency key).
Transactional Outbox + Inbox to bridge DB ↔ bus.
Per‑set ordering via orderingKey=configSet.
Poison message handling with DLQ; automated quarantine and Studio surfacing.
Back‑pressure: refresh dispatcher batches targets; SDK backoff with jitter.

Observability for Events¶

Traces: PublishConfig → DispatchRefresh → SDKApply spans; include tenantId, edition, configSet, version, region.
Metrics: ecs_refresh_latency_seconds, ecs_publish_saga_duration_seconds, ecs_refresh_fanout_total, ecs_sdk_miss_ratio.
Logs/Events: every state change emits structured logs plus the canonical event.
Audit: append‑only config_audit stream referencing event eventIds.

Security & Compliance in the Bus¶

mTLS between producers/consumers; JWS‑signed envelopes.
Per‑tenant topics/filters to prevent cross‑tenant visibility.
Payload redaction rules (no secrets/PII values; only keys and hashes).
Least‑privilege publishers (Authoring API cannot dispatch refresh without Publisher role).

Failure Modes & Compensations¶

Failure	Detection	Compensation
Schema regression in canary	Validator/SDK error rate ↑	`ConfigVersionRolledBack` → auto refresh to previous etag
Partial fan‑out	Dispatch gap metric	Reconcile job resends `RefreshSignalDispatched` to missing cohorts
Stale SDK cache	Etag mismatch	Force‑pull via targeted refresh signal with `force=true`
Ordering violation	Out‑of‑order version seen	SDK rejects < current version; recover by pull current

Event Contract Governance¶

Versioning: specVersion follows SemVer; breaking changes double‑published for grace periods.
Registry: machine‑readable JSON Schema for each eventType.
Conformance tests: contract tests per consumer; CI blocks on incompatible changes.
Documentation: generated from registry into ECS Developer Portal.

With this model, ECS achieves safe, observable, edition‑aware propagation of configuration at scale, while preserving tenant isolation, auditability, and rollbackability across regions and environments.

API & Interface Architecture¶

Design a stable, multi‑tenant, SaaS‑grade interface layer for ECS with REST + gRPC, event streaming, and gateway‑enforced policies (zero‑trust, rate limits, caching, and observability).

Design Goals¶

Simplicity for clients (SDK‑first), evolution for platform (clear versioning, deprecation).
Deterministic reads with ETag/If‑None‑Match and strong tenant scoping.
Idempotent writes with Idempotency‑Key and exactly‑once version commits.
Observable by default (OTEL traces, correlation IDs, structured errors).

Public REST Surface (selected)¶

Method	Path	Purpose	Notes
`GET`	`/v1/config`	Fetch effective config by scope	Query: `env`, `app`, `keys=*` (wildcards). Returns `etag`, `signature`, `ttl`.
`GET`	`/v1/config/versions`	List/paginate versions	`since`, `pageToken`, `pageSize`
`POST`	`/v1/drafts`	Create/extend draft change set	Requires `ecs:write:{tenantId}`
`POST`	`/v1/drafts/{id}:validate`	Validate via schema & policy	Returns violations, gates status
`POST`	`/v1/drafts/{id}:publish`	Publish → new active version	Emits events; canary options
`POST`	`/v1/refresh`	Request targeted refresh signals	Admin/ops only; throttled
`GET`	`/v1/stream/changes`	SSE stream of change hints	Long‑lived; tenant‑filtered
`GET`	`/v1/snapshots/{id}`	Download signed snapshot blob	For offline/edge use
`GET`	`/v1/schemas`	List schemas	Filter by namespace/version
`POST`	`/v1/import`	Bulk import (JSON/CSV bundle)	Async job; status polling
`GET`	`/v1/audit`	Query audit records	RFC3339 time range + filters

HTTP conventions

Headers (all calls): Authorization: Bearer …, X-Tenant-Id, X-Edition (optional), X-Trace-Id (optional).
Caching: responses include ETag and Cache-Control; clients use If-None-Match.
Errors: application/problem+json with traceId, tenantId, reasonCodes[].

gRPC Interface (excerpt)¶

syntax = "proto3";
package connectsoft.ecs.v1;

service ConfigService {
  rpc GetConfig(GetConfigRequest) returns (GetConfigResponse);
  rpc Publish(PublishRequest) returns (PublishResponse);
  rpc WatchChanges(WatchRequest) returns (stream ChangeEvent);
}

message GetConfigRequest {
  string tenant_id = 1;
  string environment = 2;  // prod|staging|dev
  string app = 3;          // optional
  repeated string keys = 4; // supports prefixes: "app/*"
  string if_none_match = 5; // ETag
}

message GetConfigResponse {
  string etag = 1;
  string version = 2;
  map<string,string> items = 3;
  bytes signature = 4; // JWS
  int32 ttl_seconds = 5;
}

SDK Contracts (language‑agnostic)¶

Initialization

EcsClient.init({ baseUrl, tenantId, tokenProvider, environment, app, cache, telemetry })

Fetch

client.get(keys: string[] | pattern, opts?: { ifNoneMatch?: string }) -> { items, etag, version, ttl, signature }

Subscribe

client.watch({ onChange(etag) => client.refresh() }) via SSE/WebSocket or bus adapter.

Policy

SDK enforces min TTL, verifies signature, and rejects older versions (version monotonicity).

Offline

Local cache with stale‑while‑revalidate; sealed snapshots for mobile/edge.

Versioning & Evolution¶

URI major versions (/v1, /v2) for breaking changes; minor features via additive fields.
Schema evolution: JSON Schema with compat class (breaking|non_breaking|additive).
Deprecation policy: announce ≥ 180 days prior; dual‑publish where possible (old/new fields); provide shim headers (Accept: application/json; ecs-version=v1).
Event contracts: SemVer in specVersion; consumers validated by contract tests in CI.

Concurrency, Idempotency, Consistency¶

Idempotent writes: Idempotency-Key header; server stores request hash → prevents duplicate commits.
Optimistic concurrency: publish/rollback require precondition (If-Match: <etag>).
Consistency: reads are cache‑first with strong etag; write acknowledgement only after outbox persisted (events durable).

API Gateway Policies¶

flowchart LR
  Client --> GW[API Gateway/WAF]
  GW -->|JWT validate, scope map| AuthZ[Policy Gate]
  AuthZ -->|quota/rate| QoS[QoS: rate, burst, circuit]
  QoS -->|ETag cache| Cache[Edge/Response Cache]
  Cache --> API[Config API]
  API --> Obs[(OTEL/Logs)]

Hold "Alt" / "Option" to enable pan & zoom

AuthN/Z: JWT validation (OIDC), scope templates ecs:read/write/admin:{tenant}; per‑path role checks.
Rate limits: per clientId/tenantId; separate buckets for read vs write; adaptive backoff with headers (Retry-After).
Caching: downstream response caching for GET with ETag; negative caching for 404 with short TTL.
DLP/PII guards: request/response body inspection on admin paths; automatic redaction in logs.
mTLS (service‑to‑service) inside cluster; WAF (bot/DDOS) at edge.

Request/Response Examples¶

Fetch effective config (conditional GET)

GET /v1/config?env=prod&app=checkout&keys=features/* HTTP/1.1
Authorization: Bearer eyJ...
X-Tenant-Id: t-123
If-None-Match: "W/42-0x8f9a"

HTTP/1.1 304 Not Modified
ETag: "W/42-0x8f9a"

Publish (idempotent)

POST /v1/drafts/42:publish
Authorization: Bearer eyJ...
X-Tenant-Id: t-123
Idempotency-Key: 2b7f-98cd

HTTP/1.1 202 Accepted
Location: /v1/config/versions?v=2025.08.24-14

Problem+JSON error

{
  "type": "https://errors.connectsoft.dev/ecs/policy-violation",
  "title": "Policy violation",
  "status": 422,
  "traceId": "f8a2…",
  "tenantId": "t-123",
  "violations": [
    {"code":"schema.max","path":"retryPolicy.maxAttempts","limit":5,"actual":9}
  ]
}

Filtering, Paging, Search¶

List endpoints support pageSize, pageToken, orderBy=createdAt desc.
Search supports prefixes & labels: keys=payments/*&labels=edition:pro,region:eu.
Time queries: RFC3339 from=…&to=… for audit/version windows.

Observability & Telemetry¶

Tracing: traceparent header propagated; spans for authz, policy, resolver, cache.
Metrics: http_server_request_duration_seconds{route="/v1/config"}, cache_hit_ratio, publish_saga_seconds.
Logs: structured with tenantId, scope, actor, result.

Security & Compliance¶

RBAC (admin/write/read) + ABAC (claims: tenantId, edition, env).
Payload signing (JWS) for responses containing config payloads; SDK verifies.
Secrets indirection only (@secret:kv://…), never plaintext in API responses.
Data residency: gateway routes to regional clusters based on tenant metadata.

Client Compatibility & Contract Tests¶

SDKs must pass conformance suites (ETag handling, signature verify, stale‑while‑revalidate behavior).
Golden recordings used to validate backward compatibility across /v1 releases.
Canary clients enabled via feature flag to test /v2 side‑by‑side.

Decommission & Deprecation Playbook¶

Announce deprecation (docs, headers: Deprecation, Sunset).
Dual‑publish new fields / endpoints; offer migration guides.
Telemetry‑based adoption tracking; alert laggards.
Freeze old write paths; finally remove after sunset date.

This API & Interface Architecture ensures stable contracts for clients, operational safety for the platform, and room to evolve without breaking tenants or ecosystem integrations.

Here’s the next section for your ECS System Architecture Blueprint, cycle 11:

Data & Storage Architecture¶

The External Configuration System (ECS) must persist critical configuration artifacts in a way that is secure, versioned, multi-tenant aware, and highly available. This section outlines the data entities, aggregate design, and storage strategies used to achieve these goals.

Core Data Entities & Aggregates¶

ECS follows DDD principles for configuration modeling:

Entity / Aggregate	Description
ConfigurationItem	Atomic unit of configuration (key, value, type, metadata).
ConfigurationSet	Grouping of items by tenant, edition, and environment.
TenantContext	Defines isolation boundary (tenant ID, edition, environment).
VersionHistory	Immutable record of changes for rollback and audit.
AuditEvent	Traceable record of read/write/refresh actions.
RefreshToken / Lease	Represents refresh session for real-time updates.

Aggregates:

ConfigurationSet is the root aggregate.
ConfigurationItem is a child entity, always managed via the set.
VersionHistory and AuditEvent are external aggregates linked via IDs.

Storage Choices¶

ECS uses a polyglot persistence strategy, optimized per concern:

SQL (Azure SQL / PostgreSQL)
- Canonical store for configuration sets, tenants, versions.
- Strong consistency and transactional guarantees.
Redis (Distributed Cache)
- Hot path read acceleration.
- TTL-based snapshots for fast retrieval at runtime.
Blob Storage (Azure Blob)
- Stores large JSON/YAML snapshots for bulk exports and rollback.
- Provides immutable, versioned archives.
Azure Key Vault (or Secrets Manager)
- Secure storage of sensitive keys, secrets, and credentials inside configs.
- Rotational policies for compliance.

Audit & Lineage¶

Every change in ECS must be traceable:

Immutable Audit Logs – all CRUD ops recorded with traceId, tenantId, actorId.
Version Lineage – each configuration version linked to parent version + diff.
Access Trails – who read/modified what, when, under what role.
Event Sourcing Option – optional replay of configuration changes for debugging or compliance.

erDiagram
    TENANT ||--o{ CONFIGURATIONSET : owns
    CONFIGURATIONSET ||--o{ CONFIGURATIONITEM : contains
    CONFIGURATIONSET ||--o{ VERSIONHISTORY : versions
    CONFIGURATIONSET ||--o{ AUDITEVENT : traces
    CONFIGURATIONITEM {
        string key
        string value
        string type
        json metadata
    }
    VERSIONHISTORY {
        string versionId
        string parentId
        string diff
        datetime timestamp
    }
    AUDITEVENT {
        string auditId
        string action
        string actor
        datetime timestamp
    }

Hold "Alt" / "Option" to enable pan & zoom

Enterprise Architect Notes¶

🔑 ECS storage must enforce tenant isolation at every level: schema, row filters, cache keys.
⚡ Redis should be treated as non-authoritative; SQL/Blob remain the source of truth.
🛡️ Key Vault integration is critical for secrets compliance (SOC2, GDPR).
📊 Observability hooks must instrument read/write latency, cache hit/miss, version drift.
♻️ Polyglot persistence aligns with ConnectSoft’s template-driven microservice design – reusable persistence templates can be applied across ECS components.

Security Architecture¶

Secure‑by‑design, zero‑trust, and multi‑tenant isolation are foundational to ECS. This section defines authentication, authorization, encryption, tenant isolation, and secure refresh channels across all layers (UI, APIs, SDKs, events, data).

Security Objectives¶

Zero‑Trust: authenticate and authorize every call; no implicit trust between services.
Tenant Isolation: hard, testable separation in data, network, and operations.
Least‑Privilege: fine‑grained scopes and roles; deny‑by‑default.
Cryptographic Integrity: signatures for payloads and events; rotation built‑in.
Compliance‑Ready: SOC2/ISO27001/GDPR controls mapped to architecture.

Identity & Authentication (AuthN)¶

Protocols: OAuth2.1 / OpenID Connect (Auth Code + PKCE for users; Client Credentials for services/agents).
Token Contents: sub, tenantId, roles[], scopes[], edition, regions[], jti, exp.
Service‑to‑Service: mTLS between gateway ↔ services; SPIFFE/SPIRE (or equivalent) for workload identity.
Human Access: SSO via ConnectSoft IdP; step‑up (MFA) for admin/approval actions.
Mobile/Web SDKs: OIDC with refresh tokens; optional certificate pinning on mobile.

Authorization (AuthZ)¶

Model: RBAC + ABAC (claims‑aware, policy‑driven).
Scopes (examples): ecs:read:{tenantId}, ecs:write:{tenantId}, ecs:admin:{tenantId}.
Permissions: resource‑scoped: {namespace}/{key} with actions {read, write, approve, admin}.
Policy Engine: centralized decision point; evaluates edition entitlements, change windows, schema/PII rules, SoD approvals.
SoD: creators ≠ approvers; enforced via policy and workflow.

Role	Typical Scopes	Notes
Tenant Reader	`ecs:read:{tenant}`	Apps/services consuming configs
Tenant Contributor	`ecs:write:{tenant}`	Draft/edit within guardrails
Tenant Approver	`ecs:approve:{tenant}`	Finalize/publish/rollback
Platform Auditor	`ecs:audit:all`	Read‑only audit across tenants
Platform Admin (limited)	`ecs:admin:platform`	Policies, plans; no direct tenant edits

Tenant Isolation¶

Data Plane: Row‑Level Security (RLS) with tenantId predicates; schema separation for premium tenants if required.
Cache Plane: cache keys prefixed {tenant}:{env}:{ns}; no cross‑tenant keys; per‑tenant TTLs.
Message Plane: tenant‑scoped topics/partitions; ACLs per topic; idempotency keys to prevent cross‑talk.
Network Plane: namespace/workload isolation; mTLS; per‑service network policies (deny‑all baseline).
Ops Plane: separate S3/Blob containers and Key Vault key sets per region/tenant tier.

Encryption Strategy¶

In Transit: TLS 1.3 everywhere (HSTS at edge; modern ciphers only).
At Rest: AES‑256 for DB, cache, blob; envelope encryption for sensitive fields.
Key Management: per‑tenant keys in KMS/Key Vault; automated rotation; audit key usage.
Field‑Level: values classified as secret stored as references @secret:; ECS never stores plaintext.
Client Cache: SDK local cache encrypted at rest; integrity verified via signed version + hash.

Secure Refresh Channels¶

Event Transport: Kafka/Azure Service Bus with TLS + SASL/mTLS; per‑tenant topics.
Message Authenticity: JWS (detached) or HMAC signature over {tenantId, version, hash, ts, nonce}.
Replay Protection: jti + nonce cache; strict timestamp skew window; idempotent handlers.
Fan‑Out: staged rollout (rings/percentage) encoded in event; SDKs honor targeting rules.
Edge Invalidation: CDN signed URLs for static bundles; short TTL; ETag + version pinning.

Security Sequences¶

A) Tokened Read (config fetch)

sequenceDiagram
  participant App as App/Service (SDK)
  participant IdP as ConnectSoft IdP
  participant GW as API Gateway (mTLS)
  participant POL as Policy Engine
  participant SVC as ECS API
  participant DB as Config DB (RLS)
  App->>IdP: OAuth2 Client Credentials (scope ecs:read:tenant-123)
  IdP-->>App: Access Token (tenantId=123, scopes, jti, exp)
  App->>GW: GET /v1/config (Bearer)
  GW->>SVC: Forward (mTLS) + token
  SVC->>POL: PDP check (tenant, edition, resource)
  POL-->>SVC: PERMIT
  SVC->>DB: RLS‑scoped read (tenantId=123)
  SVC-->>App: 200 + payload + ETag + signature

Hold "Alt" / "Option" to enable pan & zoom

B) Signed Refresh (push)

sequenceDiagram
  participant REG as ECS Registry
  participant SIG as Signer/KMS
  participant BUS as Event Bus
  participant SDK as Runtime SDK
  REG->>SIG: Sign(version, hash, tenantId, ts, nonce)
  SIG-->>REG: JWS
  REG->>BUS: Publish Ecs.ConfigChanged (JWS, headers)
  BUS-->>SDK: Deliver
  SDK->>SDK: Verify signature + nonce - reload cache

Hold "Alt" / "Option" to enable pan & zoom

Threat Model (STRIDE snapshot)¶

Threat	Mitigation
Spoofing	OIDC, mTLS, per‑workload identity, signed refresh events
Tampering	JWS/HMAC signatures, WORM audit store, optimistic concurrency
Repudiation	Immutable audit logs (WORM), `traceId`, `actorId`, `jti`
Information Disclosure	RLS, ABAC, field‑level encryption, secrets indirection
DoS	Rate limits, backpressure on bus, cache shields, circuit breakers
Elevation of Privilege	Least‑privilege scopes, SoD approvals, admin action MFA

Security Telemetry & Audit¶

Audit: append‑only (WORM), 7‑year retention for regulated tiers; SIEM exports (CEF/JSON).
Metrics: auth failures, policy denies, signature errors, drift detections, refresh lag.
Traces: end‑to‑end spans include tenantId, edition, namespace, traceId.
Alerts: anomaly detection on unusual write bursts, cross‑tenant access attempts, replay attempts.

Hardening & Supply Chain¶

SBOM for services/SDKs; verify signatures (Sigstore/COSIGN).
SAST/DAST/IAST in CI; dependency allow‑list; weekly CVE scans.
Secure Defaults: HTTP headers (CSP, HSTS, X‑Frame‑Options), JSON parser limits, request body size caps.
Secrets Ops: no secrets in env vars; short‑lived tokens; break‑glass procedure audited.

Enterprise Architect Notes¶

Treat policy decisions as first‑class artifacts; cache outcomes with short TTL for read paths, never for writes.
Prefer per‑tenant cryptographic material and storage partitions for high‑sensitivity tenants.
Make signature verification mandatory in SDKs (fail‑closed on mismatch).
Bake incident runbooks (key rotation, event key compromise, tenant isolation breach) into Ops playbooks.

Here’s the next section for the Enterprise Architecture blueprint:

Compliance & Governance Architecture¶

The External Configuration System (ECS) must embed compliance and governance requirements directly into its architecture to support multi-tenant SaaS delivery across industries with diverse regulatory obligations (GDPR, SOC2, HIPAA-ready extensions). Governance is not a separate process—it is a built-in capability spanning data, processes, and observability.

🎯 Core Compliance Requirements¶

Standard / Regulation	ECS Alignment
GDPR	Data minimization, right-to-be-forgotten, encrypted storage, consent tracking
SOC 2 Type II	Continuous monitoring, access logging, separation of duties
ISO 27001	Policy enforcement, risk management, periodic audits
HIPAA (optional)	PHI isolation, secure channels, stricter audit policies

🧩 Governance Model¶

ECS implements tiered governance checkpoints to balance agility with oversight:

Policy Definition Layer – Admins define rules (retention, access, encryption) centrally.
Execution Layer – Policies enforced in real time (e.g., config edits validated against compliance rules).
Audit Layer – Immutable event trail of all config activity.
Oversight Layer – Governance dashboards for auditors, security officers, and tenant admins.

📊 Compliance Matrix¶

Dimension	ECS Design Feature
Data Security	Encryption at rest (SQL/Blob), TLS 1.3, tenant isolation
Access Control	OpenIddict-based AuthN/AuthZ, RBAC, edition-aware policies
Auditability	Structured logs with `traceId`, `tenantId`, `userId`, exportable
Observability	Compliance-focused metrics (policy violations, audit log coverage)
Governance	Role separation: Tenant Admin vs Global Admin vs Auditor
Change Control	Config versioning, approvals workflow for sensitive configs

🔐 Governance Checkpoints¶

Config Change Validation: All config edits pass compliance validators before persistence.
Segregation of Duties: Config creators cannot approve their own changes (SOC2 principle).
Tenant Data Sovereignty: Config data can be stored regionally per tenant if required.
Right-to-Audit Hooks: Regulators and auditors can request immutable logs via APIs.

🗂️ Diagram – Compliance & Governance Layers¶

flowchart TD
  A[Policy Definition Layer] --> B[Execution Layer]
  B --> C[Audit Layer]
  C --> D[Oversight Layer]

  A -.->|Rules| B
  B -.->|Events| C
  C -.->|Reports| D

Hold "Alt" / "Option" to enable pan & zoom

Callout (Enterprise Architect Notes): ECS governance is layered: rules flow top-down, evidence flows bottom-up. This ensures policies are not aspirational but actively enforced and traceable.

✅ Summary¶

Compliance and governance are first-class citizens of ECS architecture.
The system embeds regulatory alignment, audit readiness, and tenant-specific governance models.
Governance checkpoints create traceable enforcement loops, ensuring ECS can scale into regulated and enterprise SaaS markets.

Risk Catalog (Enterprise Architecture Level)¶

The External Configuration System (ECS), as a cross-cutting SaaS backbone, must proactively assess architectural risks that could compromise scalability, resilience, security, or ecosystem adoption. This catalog enumerates risks, categorizes their impact/likelihood, and defines mitigation strategies at the Enterprise Architecture (EA) level.

🎯 Risk Categories¶

Scalability Risks
- Risk: High-frequency refresh events overload bus or caches at scale (10M+ daily).
- Impact: Latency spikes, SLA breaches.
- Mitigation:
  - Partitioned topics and per-tenant fan-out.
  - KEDA/HPA auto-scaling on dispatcher.
  - Adaptive refresh batching and backpressure.
- Risk: Resolution engine bottleneck when computing effective configs.
- Mitigation:
  - Pre-computed snapshots in Redis.
  - Incremental resolution algorithms.
  - Stress testing before rollout.

Vendor Lock-In Risks
- Risk: Over-reliance on a single provider (Azure AppConfig, CockroachDB, Redis).
- Impact: Limits portability; risk of price/service changes.
- Mitigation:
  - Provider abstraction layer with pluggable adapters.
  - Dual-write migration strategy.
  - Support open standards (CloudEvents, OpenFeature).

Data Security & Leakage Risks
- Risk: Cross-tenant data exposure via misconfigured RLS or cache pollution.
- Impact: Severe compliance breach (GDPR/SOC2 violation).
- Mitigation:
  - Row-level tenant isolation.
  - Per-tenant cache key prefixing.
  - Continuous pen-testing and automated data leak detection.
- Risk: Secrets accidentally stored inline instead of vault reference.
- Mitigation:
  - Schema classification for secret keys.
  - Enforcement: reject non-reference secret values.
  - Static/dynamic scans for sensitive patterns.

Operational Risks
- Risk: Bus outage or region partition breaks refresh propagation.
- Mitigation:
  - DLQs, retry with jitter.
  - Multi-region active-active with ≤30s drift.
  - Client SDK fallback: stale-while-revalidate.
- Risk: Audit sink overload (high-volume tenants).
- Mitigation:
  - Async write-behind buffers.
  - Tiered retention (default vs enterprise).
  - Elastic storage for WORM audit.

Adoption Risks
- Risk: Tenants continue using legacy/local configs; ECS adoption lags.
- Mitigation:
  - Migration tooling (YAML/JSON import).
  - Side-by-side support with legacy config providers.
  - Free developer tier to incentivize adoption.

📊 Risk Heatmap¶

quadrantChart
    title ECS Enterprise Risk Heatmap
    x-axis "Likelihood →"
    y-axis "Impact ↑"
    quadrant-1 "High Impact / High Likelihood"
    quadrant-2 "High Impact / Low Likelihood"
    quadrant-3 "Low Impact / Low Likelihood"
    quadrant-4 "Low Impact / High Likelihood"

    "Refresh Storms (Scaling)" : [0.7,0.9]
    "Vendor Lock-in (Azure/Redis)" : [0.6,0.7]
    "Cross-Tenant Data Leak" : [0.5,1]
    "Secrets Misuse" : [0.4,0.8]
    "Bus Outage/Partition" : [0.5,0.9]
    "Audit Sink Overload" : [0.6,0.6]
    "Low Tenant Adoption" : [0.8,0.7]

Hold "Alt" / "Option" to enable pan & zoom

✅ Summary¶

Scaling risks (refresh storms, resolution bottlenecks) are high-probability/high-impact and require architectural safeguards.
Data leakage is low-likelihood but catastrophic impact; strict isolation + audits mandatory.
Vendor lock-in is mitigated via adapter architecture and open standards.
Adoption risks must be addressed via tooling, incentives, and ecosystem integration.

Cloud-Native Deployment Model¶

The External Configuration System (ECS) must be deployed as a cloud-native, multi-tenant SaaS product capable of elastic scaling, regional compliance, and continuous delivery. This section defines the deployment topology, containerization strategy, and serverless integration patterns.

🎯 Deployment Objectives¶

Elasticity: automatically scale based on tenant load (read volume, refresh bursts).
Resilience: multi-region, active-active deployment with <30s drift.
Compliance: regional isolation for GDPR, HIPAA, or tenant-specific residency.
Portability: infrastructure defined as code (Bicep/Terraform/Helm).
Automation: GitOps + CI/CD for repeatable and auditable releases.

🌐 Core Platform: AKS (Azure Kubernetes Service)¶

Base Runtime: All ECS services containerized and deployed on AKS clusters.
Scaling:
- HPA (Horizontal Pod Autoscaler) for CPU/memory-based scaling.
- KEDA (Kubernetes Event-Driven Autoscaling) for event-based workloads (refresh dispatcher, audit consumers).
Mesh: Service Mesh (Istio/Linkerd) for mTLS, traffic splitting, observability.
CI/CD: GitOps controllers (ArgoCD/Flux) + Helm/Bicep templates.

🛠️ Container Strategy¶

Container Images:
- Built with ConnectSoft Microservice Template standards (multi-stage builds, signed SBOM, vulnerability scans).
- Published to Azure Container Registry (ACR).
Isolation: per-tenant workloads are not separate pods; ECS relies on multi-tenant aware services + strict RLS/data isolation.
Sidecars: optional containers for logging, metrics exporters, and secrets injection (Vault Agent).

⚡ Serverless Functions¶

Use Cases:
- Async jobs: Import/export, external provider sync, snapshot builders.
- Event hooks: Webhook translation, 3^rd-party integration triggers.
Platform: Azure Functions (isolated process) deployed in consumption plan.
Integration: Functions subscribe to ECS event bus (Kafka/Service Bus).
Benefits: cost-efficient for burst workloads; independent scaling.

🗂️ Deployment Topology¶

flowchart TB
  subgraph Region1["Region A (EU)"]
    AKS1[AKS Cluster]
    GW1[API Gateway]
    ST1[Config Studio SPA]
    FN1[Azure Functions Jobs]
    DB1[(SQL/CockroachDB EU)]
    RED1[(Redis Cache)]
    BUS1[(Event Bus EU)]
  end

  subgraph Region2["Region B (US)"]
    AKS2[AKS Cluster]
    GW2[API Gateway]
    ST2[Config Studio SPA]
    FN2[Azure Functions Jobs]
    DB2[(SQL/CockroachDB US)]
    RED2[(Redis Cache)]
    BUS2[(Event Bus US)]
  end

  ST1-->GW1-->AKS1
  ST2-->GW2-->AKS2
  AKS1-->DB1
  AKS1-->RED1
  AKS1-->BUS1
  AKS2-->DB2
  AKS2-->RED2
  AKS2-->BUS2
  BUS1<-->BUS2

Hold "Alt" / "Option" to enable pan & zoom

🔐 Multi-Region Strategy¶

Active-Active: Both regions serve read/write; cross-region replication ensures consistency within SLA.
Failover: DNS-based routing + global load balancer; RPO = 0, RTO < 1min.
Data Residency: Tenants pinned to specific regions (EU, US, APAC) via Tenant Registry.

📦 Packaging & Delivery¶

Helm Charts: Each ECS microservice packaged as Helm chart with dependencies (DB, cache, bus).
IaC: Azure Bicep/Terraform to provision clusters, networking, and regional stores.
GitOps: Declarative configs in Git, auto-synced by ArgoCD; version-tagged releases.

📊 Observability & Ops¶

Metrics: HPA/KEDA scaling signals, pod health, SLA compliance.
Tracing: OTEL sidecars capture service-to-service calls.
Dashboards: Grafana/Prometheus for latency, QPS, refresh lag.
Chaos Engineering: periodic pod kill/latency injection tests resilience.

✅ Summary¶

ECS is container-native on AKS with serverless augmentations for async workflows.
Elasticity achieved with HPA/KEDA, resilience with active-active multi-region.
Portability & compliance guaranteed by IaC, tenant residency mapping, and GitOps automation.

Deployment & Environment Topology¶

Objective: define how ECS runs in cloud, across environments (dev/test/stage/prod), regions (for residency), and release strategies (blue/green + canary), while preserving multi‑tenant isolation and SLA guarantees.

Environment Pyramid¶

flowchart TB
  Dev[DEV\nPer-dev namespaces\nFeature branches\nEphemeral DB/Redis\nFake IdP] --> Test[TEST\nShared QA\nContract tests\nSynthetic load]
  Test --> Stage[STAGE\nProd-like\nData masking\nChaos drills]
  Stage --> Prod[PROD\nMulti-region\nSLO enforcement\nAudited changes]

Hold "Alt" / "Option" to enable pan & zoom

EA Notes

DEV: fast iteration, template scaffolds, disposable infra.
TEST: integrates SDKs, adapters, and bus; CDC/contract tests are mandatory.
STAGE: prod parity (node pools, quotas, TLS, policies); chaos/DR drills live here.
PROD: multi‑region active‑active; error budgets drive rollout pace.

Regional Topology & Residency¶

flowchart LR
  subgraph Global
    DNS[Global DNS / GSLB]
  end

  subgraph EU["EU Region (Active)"]
    EU_GW[API Gateway (EU)]
    EU_AKS[AKS Cluster (EU)]
    EU_DB[(CockroachDB EU)]
    EU_REDIS[(Redis EU)]
    EU_BUS[(Event Bus EU)]
    EU_OBS[OTEL/Logs EU]
  end

  subgraph US["US Region (Active)"]
    US_GW[API Gateway (US)]
    US_AKS[AKS Cluster (US)]
    US_DB[(CockroachDB US)]
    US_REDIS[(Redis US)]
    US_BUS[(Event Bus US)]
    US_OBS[OTEL/Logs US]
  end

  DNS --> EU_GW
  DNS --> US_GW

  EU_GW --> EU_AKS
  EU_AKS --> EU_DB
  EU_AKS --> EU_REDIS
  EU_AKS --> EU_BUS
  EU_AKS --> EU_OBS

  US_GW --> US_AKS
  US_AKS --> US_DB
  US_AKS --> US_REDIS
  US_AKS --> US_BUS
  US_AKS --> US_OBS

Hold "Alt" / "Option" to enable pan & zoom

EA Notes

Tenants are pinned to a home region via Tenant Registry (residency policy).
Cross‑region: config versions replicate asynchronously; audit/WORM stays in‑region.
Global routing (GSLB) directs clients to nearest healthy region; write affinity remains home region by default.

In‑Cluster Layout (per region)¶

flowchart TB
  subgraph AKS["AKS Cluster (Region)"]
    subgraph Istio["Service Mesh (mTLS)"]
      API[Config API]
      RES[Resolver]
      POL[Policy & Governance]
      REF[Refresh Dispatcher]
      ADP[Provider Adapter Hub]
      AUD[Audit/Export]
      STU[Config Studio]
    end
    YARP[Edge/Gateway Ingress]
    OTEL[OTEL Collector Daemonset]
  end
  YARP --> API
  API --> RES
  API --> POL
  API --> REF
  API --> ADP
  API --> AUD
  STU --> API
  API --> OTEL
  RES --> OTEL
  REF --> OTEL

Hold "Alt" / "Option" to enable pan & zoom

EA Notes

mTLS enforced mesh‑wide; per‑workload identities; sidecars export OTEL.
Node pools separated for API, workers (resolver/refresh), and stateful operators (DB/Redis managed outside cluster when possible).

Blue/Green & Canary Strategy (per service)¶

flowchart LR
  subgraph Prod Region
    GW[API Gateway]
    subgraph Blue["Blue (current)"]
      API_B[API v1.12]
      RES_B[Resolver v1.12]
    end
    subgraph Green["Green (candidate)"]
      API_G[API v1.13]
      RES_G[Resolver v1.13]
    end
  end

  GW -- 10% → Green
  GW -- 90% → Blue

Hold "Alt" / "Option" to enable pan & zoom

Rollout Flow

Green deploy → health checks, warm caches, shadow traffic (optional).
Canary 5–10% for 15–30 min with SLO burn guard.
Ramp to 25/50/100% if stable; auto‑rollback on error thresholds.
Topology‑aware: EU and US roll independently; never flip both regions simultaneously.

EA Notes

Refresh Dispatcher and Resolver receive cohort traffic first—minimizes blast radius.
Use feature toggles for behavioral changes; deployments are reversible, config releases are rollback‑capable.

Tenant Placement & Isolation¶

flowchart TB
  subgraph Region
    subgraph ShardA["Shard A (Tenants A-M)"]
      NS1[(Namespace Pool)]
      RED1[(Redis Shard)]
      TOP1[(Bus Partitions 0..N)]
    end
    subgraph ShardB["Shard B (Tenants N-Z)"]
      NS2[(Namespace Pool)]
      RED2[(Redis Shard)]
      TOP2[(Bus Partitions N..2N)]
    end
  end

Hold "Alt" / "Option" to enable pan & zoom

EA Notes

Hash on tenantId assigns cache shard and bus partition.
VIP tenants (Enterprise) may receive dedicated shards (cache + partitions) and pinned adapter pools (e.g., Azure AppConfig).

Disaster Recovery Model¶

Scenario	Strategy	Target
Single node failure	Pod disruption budgets, multi‑AZ nodes	No impact
Redis shard failure	Replicas + sentinel/operator failover	< 1 min recovery
DB zone outage	Multi‑region Cockroach; per‑region quorum	RPO 0 / RTO ≤ 1 min
Regional loss	Global DNS failover to healthy region; read‑only for affected tenants until reconciliation	RTO ≤ 5 min
Event bus outage	Retry + DLQ; SDKs switch to poll mode	No data loss

EA Notes

Write affinity can temporarily move for VIP tenants if contractual; audit continuity is mandatory before promotion back.

Promotion Path (Env → Prod)¶

sequenceDiagram
  participant Dev as DEV
  participant Test as TEST
  participant Stage as STAGE
  participant Prod as PROD

  Dev->>Test: Image signed + contract tests
  Test->>Stage: Perf + chaos + DR drill pass
  Stage->>Prod: Blue deploy + canary 10%
  Prod->>Prod: Ramp to 100% (region A → region B)

Hold "Alt" / "Option" to enable pan & zoom

Gates

SBOM + container scan, CDC pass, perf budget pass, chaos results, rollback rehearsal, observability SLOs pre‑flight.

Operational Runbooks (high‑level)¶

Blue/Green Switch: gateway route update, cache warm, health‑probe validation, rollback macro.
Shard Rebalance: migrate tenant hash ranges; drain/rehash Redis keys safely.
Regional Failover: DNS cutover, publish freeze, policy to serve LKG with stale=true, reconciliation job.
Bus Partition Hotspot: split partitions for hot tenants; replay DLQ with throttling.

Readiness Checklist¶

Tenant→region mapping enforced at gateway; residency verified.
Canary policies per service defined; error budget alerts wired.
DR runbooks exercised in STAGE monthly; evidence stored.
Shard capacity workbook (cache/bus/db) updated quarterly.
Per‑region config snapshot warmers in place ahead of deployment.

Enterprise Architect Notes

Keep deployments predictable and regionally independent.
Use traffic splitting + feature flags to separate deploy risk from configuration risk.
All topology decisions must be observable: dashboards for rollout, shards, and residency compliance.

Network & Infrastructure Blueprint¶

The External Configuration System (ECS) requires a secure, observable, and scalable network and infrastructure fabric to support multi-tenant SaaS delivery. This section outlines how ECS services interact over the network, how isolation is enforced, and how traffic flows from edge to core.

🎯 Objectives¶

Enforce zero-trust networking with encryption and identity at every hop.
Provide service discovery and routing via a service mesh.
Expose ECS APIs through a global API gateway with policy enforcement.
Support tenant and region-level isolation for compliance.
Ensure high availability and observability across regions.

🔑 Key Components¶

API Gateway (Global + Regional)
- Central entry point for ECS API traffic.
- OIDC/OAuth2 token introspection.
- Enforces quotas, rate limiting, and WAF rules.
- Canary/blue-green rollout supported at gateway layer.
Service Mesh (Istio/Linkerd)
- mTLS between services (SPIFFE identities).
- Traffic routing: canary releases, A/B routing, retries, circuit breakers.
- Sidecar injection for observability and policy enforcement.
Network Segmentation
- Public Zone: API Gateway, Config Studio SPA (UI).
- Service Zone: ECS Core services (API, Resolver, Policy, Audit, Refresh).
- Data Zone: SQL DB, Redis, Blob, WORM Audit Store.
- Messaging Zone: Event bus clusters.
- Deny-by-default ingress/egress between zones; only allow explicit flows.
Regional Isolation
- Separate VNETs per region (EU, US, APAC).
- Cross-region sync restricted to replication endpoints only.
- Tenant registry directs requests to correct region via Global Load Balancer (GLB).

📐 Traffic Flow¶

flowchart LR
  Client[Client SDK/App] --> CDN[Edge CDN/Proxy]
  CDN --> APIGW[Global API Gateway]
  APIGW --> WAF[WAF/Rate Limits]
  WAF --> Mesh[Service Mesh]
  Mesh --> API[Config API Service]
  Mesh --> POL[Policy Service]
  Mesh --> RES[Resolver Service]
  Mesh --> REF[Refresh Dispatcher]
  Mesh --> AUD[Audit Service]
  API --> DB[(SQL DB)]
  RES --> RED[(Redis Cache)]
  REF --> BUS[(Event Bus)]
  AUD --> WORM[(WORM Audit Store)]

Hold "Alt" / "Option" to enable pan & zoom

Flow Notes

Clients → CDN → Gateway: all requests authenticated & authorized.
Gateway → Mesh: routing to ECS services.
Mesh → Data Zone: only whitelisted ports; TLS enforced.
Refresh events → Event Bus → Clients (pull or SSE).

🔒 Security & Isolation Controls¶

Perimeter Security: WAF, DDoS protection at gateway.
Mesh Security: mTLS + workload identity (cert rotation automated).
Data Isolation:
- Tenant-scoped row filters in SQL.
- Cache namespace per tenant/env.
- Per-tenant topics in event bus.
Secrets Management: Only injected via Vault/KMS sidecars, not env vars.

📊 Observability & Diagnostics¶

Tracing: OTEL spans from gateway → mesh → services → DB.
Metrics: per-zone latency, QPS, cache hit rate, failed policy checks.
Dashboards: traffic flows by tenant/region; SLA heatmaps.
Diagnostics: packet capture & service flow replay enabled in staging clusters.

🌍 Multi-Region & HA¶

Global Load Balancer (GLB): routes traffic to closest region.
Failover: GLB detects outage; reroutes to healthy region in <1 min.
Event Bus: geo-replicated clusters; cross-region event drift <30s.
Edge CDN: caches static bundles; fallback to last-known config snapshot during regional outage.

✅ Summary¶

ECS network fabric is zero-trust, segmented, and observable.
Service Mesh provides routing, resiliency, and security.
API Gateway provides policy enforcement and external exposure.
Regional isolation + global routing ensure compliance and resilience.

Observability & Telemetry Architecture¶

ECS adopts an observability‑first posture. Every interaction—API call, policy decision, snapshot build, refresh fan‑out, SDK fetch—is traceable, measurable, and auditable. This section defines the traces, metrics, logs, and audit observability required to operate ECS at multi‑tenant SaaS scale.

Objectives¶

End‑to‑end tracing across gateway → services → data → bus → SDKs.
Actionable SLIs/SLOs that map to product SLAs and error budgets.
Tenant‑aware telemetry (dimensions: tenantId, edition, environment, namespace).
Low‑cardinality, high‑signal metrics with exemplars linking to traces.
Immutable, queryable audit integrated with operational views and SIEM.

Telemetry Topology¶

flowchart LR
  subgraph Workloads
    GW[API Gateway]
    API[Config API]
    RES[Resolver]
    POL[Policy]
    REF[Refresh Dispatcher]
    SDK[Client SDKs]
  end

  subgraph Collect["OTel Collectors"]
    COLR[Regional Collector]
    COLE[Edge/Sidecar Collectors]
  end

  subgraph Sinks
    PM[Prometheus or Mimir]
    LG[Logs Store - Loki/Elastic]
    TR[Trace Store - Tempo/Jaeger]
    AZ[Cloud Monitor Export]
    SIEM[SIEM - Sentinel/Splunk]
  end

  GW-->COLE
  API-->COLE
  RES-->COLE
  POL-->COLE
  REF-->COLE
  SDK-->COLR

  COLE-->COLR
  COLR-->PM
  COLR-->LG
  COLR-->TR
  COLR-->AZ
  LG-->SIEM

Hold "Alt" / "Option" to enable pan & zoom

Standards: OTLP for export; OpenTelemetry SDKs in all services and instrumented ECS client SDKs.

Tracing (OpenTelemetry)¶

Span model (canonical names):

gw.request (API Gateway)
ecs.api.config.get|put|publish|rollback
ecs.resolver.computeSnapshot
ecs.policy.evaluate
ecs.refresh.fanout
ecs.sdk.fetch / ecs.sdk.apply

Required attributes (on every span):

tenant.id, tenant.edition, env, namespace, config.keys.count
version, etag, trace.id, actor.id (if human), client.type (sdk/web/agent)
outcome (ok|deny|error|timeout|stale)
refresh.mode (push|poll|edge-invalidate) when applicable

Propagation: W3C TraceContext; gateway injects/validates. SDKs propagate traceparent on pull and include trace_id in push acknowledgements.

Sampling strategy:

Head‑based 10–20% for steady‑state.
Tail‑based keep rules:
- latency > p95, HTTP 5xx, policy deny, refresh lag > 5s, cross‑tenant suspicion.
Exemplars on key metrics link to long traces.

Metrics (RED + USE, tenant‑aware)¶

Golden signals & SLIs (per region + tenant roll‑ups):

Metric (name)	Definition / Notes	SLO (example)
`ecs_config_fetch_latency_ms`	p50/p95/p99 latency of GET config	p95 ≤ 50ms (cache hit)
`ecs_refresh_propagation_ms`	publish→SDK apply delta	p95 ≤ 2000ms
`ecs_cache_hit_ratio`	edge/cache hits ÷ total reads	≥ 0.90
`ecs_api_error_rate`	5xx + policy‑deny (distinct) per minute	≤ 0.1% (5xx only)
`ecs_snapshot_build_duration_ms`	resolver snapshot compute time	p95 ≤ 300ms
`ecs_policy_denies_total`	count by policy id/tenant	alert on spike
`ecs_refresh_events_total`	fan‑out volume by tenant/env	capacity planning
`ecs_audit_writes_queue_depth`	audit write buffer depth	no sustained backlog
`ecs_drift_detected_total`	provider drift incidents	zero at steady‑state

Dimensional constraints: restrict high‑cardinality tags—hash/keys lists are not labels; aggregate into counts and link exemplars for deep dives.

Logging (structured, privacy‑safe)¶

JSON logs with fields: ts, level, message, trace_id, span_id, tenant.id, actor.id, event.type, outcome, policy.id, version, request.id, src, svc.
PII redaction at source; secrets never logged (validators enforce).
Correlation: every log contains trace_id and tenant.id; error logs attach exemplar link to trace in UI.

Audit Observability¶

WORM (append‑only) audit store with schema: audit_id, ts, actor_id, actor_type, tenant_id, resource, action, before_hash, after_hash, policy_outcome, reason, trace_id.
Search: indexed by tenant_id, resource, action, actor_id, ts.
Integrity: Merkle chain or periodic signed checkpoints; verification job visualized in dashboard.
SIEM export: near‑real‑time stream of normalized audit events (CEF/JSON), with playbooks for high‑risk actions (mass rollback, cross‑tenant reads).

SLOs & Error Budgets¶

flowchart TD
  SLI[SLIs: latency, availability, refresh lag] --> SLO[SLO Targets]
  SLO --> EB[Error Budget - monthly]
  EB --> Guard[Auto-guardrails: slow-rollouts, feature freeze]
  EB --> Page[PagerDuty: paging policy levels]

Hold "Alt" / "Option" to enable pan & zoom

SLO policy examples:
- Availability: 99.95% regional.
- Refresh lag p95: ≤ 2s.
- Fetch latency p95: ≤ 50ms (edge hit), ≤ 150ms (miss).
Burn alerts: 2%/1h (warning), 5%/1h (critical) of monthly error budget.

Dashboards (operator‑ready)¶

Platform Overview: traffic, error rate, latency heatmaps, refresh lag, cache hit.
Tenant Health: SLIs by tenant; policy denies; quota usage; adoption.
Rollout Command Center: change velocity, staged rollout status, rollback rate.
Security & Compliance: auth failures, cross‑tenant access attempts, audit integrity, drift detection.
Provider Adapters: sync lag, error codes, throughput, backpressure.

Alerting & Runbooks¶

Alerts:
- HighRefreshLag: ecs_refresh_propagation_ms_p95 > 2s for 5m.
- CacheMissSurge: ecs_cache_hit_ratio < 0.8 for 10m.
- PolicyDenySpike: ecs_policy_denies_total{tenant=…} sudden Δ.
- DriftDetected: non‑zero over baseline.
Runbooks link from alerts: refresh queue inspection, bus partition health, adapter failover, snapshot rebuild, policy rollback.

Example: Correlated Fetch Trace¶

sequenceDiagram
  participant App as SDK
  participant GW as API Gateway
  participant API as Config API
  participant RES as Resolver
  participant RED as Redis
  App->>GW: GET /v1/config (traceparent)
  GW->>API: forward (span gw.request)
  API->>RED: cache get (span ecs.cache.get)
  alt miss
    API->>RES: computeSnapshot (span ecs.resolver.computeSnapshot)
    RES-->>API: snapshot (etag, version)
  end
  API-->>App: 200 (etag, version, signature)
  Note over App,API: trace_id correlates logs, metrics with exemplars

Hold "Alt" / "Option" to enable pan & zoom

Compliance & Governance Hooks in Observability¶

Policy evidence (approval IDs, rules applied) attached to spans/logs for publish/rollback flows.
Data residency labels on metrics to ensure regional SLO visibility.
Access transparency: per‑tenant audit dashboard; export API with signed reports.

Enterprise Architect Notes¶

Bake observability contracts into service templates (span names, attributes, metric names).
Enforce budget‑friendly cardinality with linting in CI.
Make tail‑sampling default for error/slow paths to keep costs in check while retaining signal.
Treat audit as a first‑class data product—verifiable, queryable, and integrated with ops.

Resiliency & Reliability Patterns¶

ECS must degrade gracefully, isolate failures, and preserve SLAs during partial outages, spikes, and downstream instability. This section defines circuit breaking, retries/timeouts, chaos readiness, and DLQ handling across API, Resolver, Provider Hub, Refresh Dispatcher, Gateway/Edge, and Audit planes.

Objectives¶

Contain blast radius with bulkheads and backpressure.
Prefer availability over freshness (serve cached/snapshotted configs when upstream is impaired).
Idempotent, replay‑safe messaging with clear DLQ triage.
Automated recovery guided by SLO/error‑budget policies.

Cross‑Cutting Patterns¶

Timeouts & Retries (with Jitter)¶

Defaults (guidance):
- Edge cache read: 20–40 ms timeout, no retry.
- Redis read: 50–100 ms, 1 retry (jittered).
- DB (read): 150–300 ms, 1 retry (bounded).
- Provider write/publish: 300–800 ms, 3 retries (exponential + jitter).
Rules: never retry non‑idempotent operations; use idempotency keys on write paths.
Budgets: retries consume a per‑request latency budget; if exceeded, fail fast with graceful fallback.

Circuit Breakers¶

States: Closed → Open (on error rate/latency spike) → Half‑Open (probe).
Trip signals: p95 latency > threshold for N windows, 5xx surge, connection exhaustion.
Fallbacks: serve stale snapshot or last known good (LKG) response; deny mutations safely.

Bulkheads & Backpressure¶

Isolate pools per dependency (DB/Cache/Bus/Provider); independent resource quotas.
Queue caps with shed load policy for non‑critical work (e.g., analytics exports).
Producer throttling when consumer lag grows (refresh fan‑out).

Exactly‑Once/At‑Least‑Once Semantics¶

Bus: at‑least‑once delivery.
Consumers: idempotent by (tenantId,eventId,version); processed_events table for dedupe.
Producers: transactional outbox to avoid dual‑write anomalies (DB commit + event publish).

Component‑Level Resilience¶

Component	Failure Modes	Primary Strategies
Gateway & Edge Cache	Origin latency, cache stampede, WAF false positives	Stale‑while‑revalidate, request coalescing, ETag/version pinning, per‑tenant rate limits
Config API	DB slow/locked, policy latency	Timeout + limited retry, open circuit → serve LKG from cache, async policy hints
Resolver	Snapshot rebuild spike, hot key contention	Pre‑computed snapshots, partial rebuilds, concurrency caps, queueing with backpressure
Provider Hub	Provider outage/throttle, consistency drift	Circuit to secondary provider, read‑through cache, drift detection + quarantine, dual‑write cutover
Refresh Dispatcher	Bus partition lag, fan‑out storms	Partitioned topics (tenant/env), adaptive batch size, retry with DLQ, consumer lag alarms
Audit & Observability	Sink backpressure, log explosion	Async buffers, lossless mode for regulated tiers, dynamic sampling, backoff to cold path

Resiliency Flows¶

A) Retry + Circuit + Fallback (read path)¶

flowchart LR
  Client-->Edge[Edge Cache]
  Edge -- miss --> API[Config API]
  API -->|read| Cache[(Redis)]
  Cache -- hit --> API
  Cache -- miss --> Resolver[Snapshot Resolver]
  Resolver --> DB[(SQL)]
  API --> Client
  API -. on error/latency .-> CB{Circuit State}
  CB -- open --> LKG[Last-Known-Good Snapshot]
  LKG --> Client

Hold "Alt" / "Option" to enable pan & zoom

Behavior: On elevated error/latency, circuit opens and API returns signed LKG with short TTL and stale=true hint; background refresh continues.

B) Outbox → Bus → Idempotent Consumer (write/refresh path)¶

sequenceDiagram
  participant API as Config API
  participant DB as DB (Outbox)
  participant BUS as Event Bus
  participant REF as Refresh Consumer
  API->>DB: Commit config + outbox record
  loop publisher
    API->>BUS: Publish outbox (tx-aware)
  end
  BUS-->>REF: Ecs.ConfigChanged (tenant,version,eventId)
  REF->>REF: Idempotency check (eventId)
  REF->>Clients: Fan-out refresh

Hold "Alt" / "Option" to enable pan & zoom

Guarantee: At‑least‑once on the bus; effectively once via idempotent consumers.

DLQ Handling¶

DLQ Pipeline¶

flowchart TB
  Fail[Failed Message] --> Classify[Classifier]
  Classify -->|Transient| RetryQ[Retry Queue]
  Classify -->|Poison| Quarantine[Quarantine Topic]
  Classify -->|Policy| Manual[Manual Review]
  RetryQ -->|backoff schedule| BUS[(Main Topic)]
  Quarantine --> Report[Auto Report + Ticket]
  Manual --> Fix[Playbook/Hotfix] --> BUS

Hold "Alt" / "Option" to enable pan & zoom

Transient (timeouts, throttles): exponential backoff (e.g., 30s, 2m, 10m, 1h) with jitter.
Poison (schema, serialization): quarantine; require code/config fix.
Policy (authorization/guardrail): manual review; may reclassify or discard.
SLAs: DLQ drained ≤ 30 min for transient classes; quarantine triage within 4 h.

Telemetry: per‑tenant DLQ depth, retry success ratio, time‑to‑drain.

Chaos Readiness¶

Fault Injection Plan¶

Latency injection: DB + cache + bus; verify circuit trips and SLOs hold.
Dependency blackhole: provider adapter returns ECONNREFUSED; ensure secondary cutover.
Thundering herd: force mass refresh; validate dispatcher backpressure and SDK self‑throttle.
Regional loss: simulate region outage; confirm GLB failover + data residency rules.

flowchart LR
  Chaos[Fault Injector] --> DB
  Chaos --> Cache
  Chaos --> Bus
  Chaos --> Provider
  Observe[SLI Monitors] --> Guard[Auto Guardrails]
  Guard --> Orchestrator[Rollout/Freeze Controls]

Hold "Alt" / "Option" to enable pan & zoom

Guardrails: auto‑reduce rollout velocity, pause non‑critical jobs, raise protection rules when error‑budget burn > thresholds.

Policy‑Driven Auto‑Mitigation¶

Auto‑freeze writes when audit sink backlog > N or DB writes exceed p95 SLA.
Slow‑roll refresh (cap batch size, increase inter‑batch delay) when consumer lag persists.
Prefer regional reads when cross‑region latency > threshold.
Downgrade to cached bundles for SPA/mobile when origin error‑rate spikes.

Health Probes & Canaries¶

Probes:
- Liveness: process + dependency ping (non‑intrusive).
- Readiness: synthetic tenant‑scoped read with RLS; reject traffic until green.
Canary: per region/tenant cohort; compare SLO deltas before full rollout.

Runbooks (extract)¶

CB_OPEN_PROVIDER: verify adapter health → force secondary route → schedule warm‑up → re‑probe half‑open.
DLQ_SURGE: inspect classifier stats → bump backoff → patch poison fix → replay quarantine.
REFRESH_LAG: increase partitions, widen consumer group, reduce per‑event payload, throttle publishers.
CACHE_STAMPEDE: enable collapsed forwarding at edge, extend TTL temporarily, warm keyset via job.

SLO‑Linked Reliability¶

flowchart TD
  Events[Errors/Lag/Latency] --> Detect[SLI Breach Detectors]
  Detect --> Decide[Policy Engine (Guardrails)]
  Decide --> Act[Automations: throttle/freeze/failover]
  Act --> Observe[Error Budget Burn]
  Observe --> Decide

Hold "Alt" / "Option" to enable pan & zoom

Error budget policy: automatic actions at warning (2%/h) and critical (5%/h) burn, with human override.

Enterprise Architect Notes¶

Bake resilience defaults (timeouts, circuits, retries) into the service template; forbid ad‑hoc overrides without ADR.
Treat snapshots/LKG as first‑class to uphold availability during upstream faults.
Make DLQ classification deterministic and observable; integrate with incident tooling.
Chaos experiments must be continuous (weekly canaries, monthly game‑days) and SLO‑driven.

Performance & Scalability Model¶

Design objective: guarantee predictable, low‑latency reads and fast, safe propagation of config changes for thousands of tenants, across regions, under bursty workloads—without compromising isolation or cost efficiency.

SLAs & SLOs (by Edition/Tier)¶

Dimension	Free / Dev	Pro	Enterprise
Availability (per region)	99.5%	99.9%	99.95%
Read Latency p95 (cache hit)	≤ 80 ms	≤ 60 ms	≤ 50 ms
Read Latency p95 (cache miss)	≤ 200 ms	≤ 150 ms	≤ 120 ms
Publish→Refresh Propagation p95	≤ 5 s	≤ 3 s	≤ 2 s
Publish Throughput (sustained)	5 ops/s	20 ops/s	50+ ops/s (pooled)
Regional RTO / RPO	5 min / ≤ 15 s	2 min / 0	1 min / 0
Support for Data Residency	—	Per‑region	Contracted regions
SLA Credits	—	Standard	Enhanced + root‑cause report

Enterprise Architect Notes SLAs are enforced per region; multi‑region availability is a composite of regional SLAs plus global routing.

Traffic Model & Capacity Targets¶

Baseline Assumptions (per region)¶

Tenants: 3,000 (grows to 10k+)
Active services/apps (SDK clients): 120k
Read/Write mix: 99.5% reads / 0.5% writes
Average keys fetched per call: 12 (pattern or bundle)
Daily refresh events: 5–20M (fan‑out hints; SDKs pull deltas)

QPS Targets¶

Steady‑state read QPS: 8–12k QPS/region
Burst read QPS (refresh storm): 30–50k QPS/region for ≤ 10 min
Write QPS (publish/draft ops): 40–200 QPS pooled

Capacity Formulae (planning)¶

Edge capacity ≈ targetQPS / hitRatio
Primary store RPS ≈ targetQPS * (1 - hitRatio)
Bus partitions ≥ (refresh_events_per_sec / partition_target_throughput)
Cache memory (GB) ≈ activeSnapshots * avgSnapshotSize * replicationFactor

EA Notes Plan for ≥ 90% cache hit ratio at edge; primary store should be sized for ≤ 10% miss traffic plus write load.

Multi‑Tier Caching Strategy¶

flowchart LR
  SDK[Client SDK] --> Edge[Edge CDN / Response Cache]
  Edge -->|MISS| GW[API Gateway Cache]
  GW -->|MISS| Redis[(Redis: Snapshot Cache)]
  Redis -->|MISS| Resolver[Effective Config Resolver]
  Resolver --> SQL[(SQL/Cockroach DB)]
  SDK <-- Edge

Hold "Alt" / "Option" to enable pan & zoom

Tier‑0 (SDK local): in‑process LRU with ETag/version pinning and stale‑while‑revalidate (SWR).
Tier‑1 (Edge CDN/Response Cache): signed bundles and hot endpoints; TTL 30–120 s, SWR enabled.
Tier‑2 (Gateway cache): short TTL response cache + negative caching (404) 3–5 s.
Tier‑3 (Redis): ResolvedSnapshot objects (per {tenant}:{env}:{ns}:{app}), TTL 5–15 min, stampede protection (single‑flight).
Authoritative store: SQL/Cockroach. Snapshots are rebuildable → non‑authoritative caches.

Cache Invalidation

Push: RefreshSignal invalidates Redis keys + Edge paths.
Pull: SDKs perform conditional GET with If-None-Match; 304s keep hot path cheap.

Scaling Strategies¶

Horizontal & Event‑Driven Autoscaling¶

API/Resolver: HPA on RPS, latency p95, CPU, secondary on cache miss ratio.
Refresh Dispatcher: KEDA on bus lag and messages/sec; adaptive batch size.
Adapter/Provider pods: HPA on throttle/429 rate and RTT.
Audit/Aggregators: decouple to write‑behind queues; scale by queue depth.

Partitioning & Sharding¶

Tenant sharding: consistent hash by tenantId for cache and bus partitions.
DB partitioning: by tenantId, environment; optional table sharding for hot namespaces.
Edge keyspace: path prefix /t/{tenant}/e/{env}/ns/{ns}/app/{app} for precise invalidation.

Backpressure & Load Shedding¶

Refresh fan‑out: bounded concurrency; staged cohorts (rings) for large tenants.
Write throttles: per‑tenant publish rate limits; slow mode when error budget burning.
Read overload: serve signed LKG (last known good) with stale=true hint; log exemplars.

Performance Budgets¶

Budget	Target	Notes
SDK cold start	≤ 150 ms to first hit (edge)	Includes token fetch & DNS warmup (client‑side)
Cache rebuild	≤ 300 ms p95 per snapshot	Resolver + DB roundtrip under nominal load
Publish pipeline	≤ 1.5 s p95 to first cohort	Draft→validate→persist→signal (excluding approvals)
Edge invalidation	≤ 500 ms	PoP purge for affected paths
Cross‑region drift	≤ 30 s	Event replication + revalidation

EA Notes Treat budgets as contracts across teams. Regressions require either optimization or scope/feature trade‑offs.

Read Path Optimization¶

Shape the payload: allow key prefixes and server‑side projection; avoid over‑fetch.
Compression: enable gzip/br on bundles; snapshot JSON normalized; consider Zstd for blobs.
Signature verify: SDK verification off the hot path using async prefetch; fail‑closed on mismatch.
Egress minimization: 304s via ETag + strong validators; delta responses where feasible.

Publish/Refresh Throughput¶

sequenceDiagram
  participant Studio as Config Studio
  participant API as API
  participant DB as SQL
  participant Outbox as Outbox
  participant Bus as Event Bus
  participant Ref as Refresh Fanout
  participant Edge as Edge/Redis
  Studio->>API: Publish Draft (idempotent)
  API->>DB: Persist Version (txn)
  API->>Outbox: Enqueue ConfigChanged
  Outbox->>Bus: Durable publish (retries)
  Bus->>Ref: Consume + partition by tenant
  Ref->>Edge: Invalidate cache paths
  Ref->>SDKs: Push hints (SSE/WebSocket)

Hold "Alt" / "Option" to enable pan & zoom

Throughput knobs: bus partitions per region (min 48 for 20M/day), fan‑out batch size (e.g., 500–1000), retry with jitter, DLQ on poison.

Edition & Tenant Segmentation¶

Pro/Ent tenants may receive dedicated cache shards and higher Edge TTL.
Free/Dev share multi‑tenant shards with stricter rate caps.
VIP tenants (Enterprise) can pin to premium adapters (e.g., Azure AppConfig) with independent scaling.

Perf Test Plan (repeatable)¶

Workload Mix (per region)

80% GET /v1/config (randomized key sets, varied TTL)
15% SSE keepalive + delta pulls
5% writes: drafts, validate, publish (with approvals stubbed)

Scenarios

Steady Read: 10k QPS, 95% hit ratio.
Refresh Storm: 200 publishes → fan‑out to 100k SDKs within 120 s.
Cache Flush: rolling Redis restart; validate stampede protection.
Regional Partition: fail EU bus; ensure LKG served; catch‑up < 60 s on restore.
Hot Namespace: single config set 5x normal load; ensure fair scheduling.

Success Criteria

Meets SLOs; zero cross‑tenant leakage; no unbounded queues; error budget intact.

Observability for Scale¶

Golden metrics: cache_hit_ratio, fetch_latency_p95/p99, refresh_propagation_p95, publish_saga_duration, bus_consumer_lag, redis_cpu/memory, db_lock_wait, policy_deny_rate.
Autoscale signals:
- API: rps, latency_p95, cache_miss_ratio
- Fan‑out: consumer_lag, events/sec
- Resolver: snapshot_build_duration, concurrency_queue_depth
Dashboards: Read Hot Path, Publish Pipeline, Refresh Fan‑Out, Tenants Top‑N, Region Drift.

Cost Efficiency Levers¶

Prefer edge and gateway caching to reduce origin QPS.
Bundle frequently co‑requested keys into signed snapshots.
Adaptive sampling for traces/logs; keep exemplars for slow/error paths.
Tiered storage for audit/snapshots (hot → cool → archive) with lifecycle rules.

Guardrails & Limits (per tenant defaults)¶

Limit	Free/Dev	Pro	Enterprise
Read QPS (sustained)	50	500	2,000+
Refresh signals / min	300	5,000	25,000
Keys per namespace	500	5,000	25,000
Max snapshot size	256 KB	1 MB	5 MB
Concurrent publishes	1	3	10

EA Notes Guardrails are enforced at gateway and dispatcher. Breaches trigger soft‑throttle (429 + backoff hints) and advisory notices.

Resilience Under Load (degradation policy)¶

Protect reads → serve signed LKG; mark stale=true, shorter TTL.
Throttle writes → queue non‑urgent publishes, freeze large rollouts.
Prioritize VIP tenants → dedicated partitions & cache shards.
Shed non‑critical work → analytics exports, deep diffs, background syncs.

Ready‑to‑Implement Checklist¶

HPA/KEDA policies defined from golden metrics.
Cache keys & invalidation matrix documented and tested.
Bus partitions sized; DLQs + replay runbooks in place.
Perf test harness (steady/burst/failure) automated in CI.
Capacity workbook: QPS→pods→instances→cost maintained per region.
SLOs codified as alerts with error‑budget burn policies.

Technology Stack Selection¶

This section defines the reference technology stack for ECS, aligned with ConnectSoft templates and libraries, and optimized for SaaS-grade scale, security, and operability.

Stack Overview (build/run/observe)¶

Layer	Choice	Why it fits ECS
Language/Runtime	.NET 9 (C# 13), ASP.NET Core Minimal APIs	First-class support for high-throughput services, native AOT where beneficial, unified stack with ConnectSoft templates; clear upgrade path from .NET 8 LTS.
Service Template	ConnectSoft Microservice Template (Clean Architecture: Domain, Application, Infrastructure, Interface)	Enforces layering, testability, modularity; repeatable codegen for 3k+ services across ecosystem.
Persistence (Primary)	SQL / CockroachDB	Strong consistency, SQL ergonomics, multi-region capabilities; row-level tenancy patterns.
ORM / Data Access	NHibernate (primary), EF Core (select adapters)	NH for advanced mapping, batching, second-level cache; EF Core optionally used where provider ecosystems (e.g., AppConfig, non-relational) are dominant.
Caching	Redis (Clustered)	Hot-path snapshot cache, pub/sub hints, predictable latency, mature client ecosystem.
Messaging	MassTransit + Azure Service Bus (topics) / Kafka (high-fanout refresh)	Vendor-agnostic bus abstraction; ASB for lifecycle/governance topics, Kafka/EH optional for refresh-scale.
API Gateway	YARP / Cloud Gateway (e.g., APIM/Gateway API)**	Path-based routing, mTLS, rate limits, ETag and response caching on read path.
Security & Secrets	OIDC/OAuth2 (IdP), Key Vault / Secrets Manager	Zero-trust, per-tenant scopes; secret indirection (`@secret:`) and envelope encryption.
Observability	OpenTelemetry (traces/metrics/logs), Prometheus/Grafana, Elastic/Cloud Logs	Unified tracing across publish→refresh→SDK; SLO dashboards and burn-rate alerts.
Packaging/Deploy	Containers, Helm, AKS (or equivalent); KEDA/HPA	Cloud-native elasticity; event- and CPU-based autoscale; multi-region active-active.
CI/CD	GitHub Actions / Azure DevOps, container scanning, policy-as-code	Supply chain hardening, gates for architecture & security compliance.

Component-by-Component Justification¶

.NET 9 + ConnectSoft Templates¶

Performance & ergonomics: ASP.NET Core minimal APIs + native AOT where applicable reduce cold-start and memory footprint on stateless edges.
Consistency: One runtime across API, workers, and adapters simplifies skills, reuse, and SRE playbooks.
Template synergy: The microservice template bakes in Clean Architecture, CQRS options, dependency inversion, and test harnesses—accelerating safe codegen and uniform quality.

NHibernate (primary) + EF Core (select)¶

NHibernate: mature mapping for complex aggregates (version history, audit shadows), batching and cache patterns beneficial for snapshot builds; flexible custom SQL for CockroachDB.
EF Core: kept for provider ecosystems and rapid adapter work (e.g., Microsoft.*), or where migrations/tooling convenience outweighs advanced NH patterns.
Guideline: ECS domain services (Authoring/Serving/Policy) favor NH; adapter services may use EF Core to leverage provider SDKs and quicker scaffolding.

Redis¶

Hot-path cache for ResolvedSnapshot {tenant, env, ns, app} with stampede protection, SWR, and pub/sub hints.
Operationally simple: observable memory footprint, predictable latency under extreme read QPS.

MassTransit + Azure Service Bus / Kafka¶

Abstraction: single programming model, pluggable backends.
Separation of concerns: ASB topics for lifecycle/governance (ordered, moderate volume); Kafka/Event Hubs (optional plane) for high-fanout refresh signals.

Reference Module Mapping (Template → Capability)¶

ECS Capability	Template Module(s)	Libraries / Notes
Config API (CRUD/versioning)	`Service.Api`, `Service.Application`, `Service.Domain`	Validation, Idempotency, OpenAPI, OTEL middleware
Resolver & Snapshot Builder	`Service.Worker`, `Service.Domain`	NHibernate, pipeline behaviors, Redis client
Policy & Approvals	`Service.Api`, optional `Service.Rules`	JSON Schema/OPA adapters, audit decorators
Refresh Dispatcher	`Service.Worker`	MassTransit consumers, partitioning by tenant
Provider Adapters	`Service.Adapter`	EF/NH mixed; anti-corruption mapping
Audit & Export	`Service.Worker`, `Service.Api`	WORM sink, SIEM exporters, tiered storage
SDK Distribution	`Service.Static`	NuGet/NPM pipelines, semver gate

Version & Support Policy¶

Runtime: Target .NET 9 for core services; maintain .NET 8 LTS compatibility path for adapters/SDKs where required by customers.
Database: CockroachDB v24+ (or equivalent) with multi-region tables; validated against PostgreSQL compatibility for local dev.
Redis: 7.x cluster with TLS; memory and eviction policies documented per tier.
MassTransit: current major supporting both Service Bus and Kafka transports.
Backward Compatibility: API and event versioning (semantic); SDKs accept minor upgrades without breaking.

NFR Mapping (stack ↔ qualities)¶

Quality	Stack Feature	Outcome
Latency	Redis hot cache, ETag + SWR, native AOT	p95 read hit ≤ 50 ms
Throughput	Minimal APIs, batching (NH), async I/O	>10k QPS/region sustained
Resilience	MassTransit retries + DLQ, outbox/inbox	No lost events / controlled replay
Security	OIDC scopes/claims, mTLS, KV integration	Zero-trust by default
Observability	OTEL end-to-end, exemplars, RED/USE dashboards	Rapid triage & SLO governance
Portability	Provider adapters + anti-corruption layer	Avoids lock-in; tenant-level routing

Operational Playbooks Enabled by the Stack¶

Dual-plane messaging (ASB + Kafka/EH) for clean separation of governance vs. high-fanout refresh.
Blue/Green + canary via gateway and dispatcher cohorting; automated rollback saga.
Data residency via CockroachDB multi-region + tenant routing at gateway.
Cost control via Redis tiering, adaptive tracing, edge caching of signed bundles.

Risks & Mitigations (tech selection)¶

Risk	Impact	Mitigation
.NET 9 non‑LTS window vs. conservative customers	Slower adoption for some tenants	Keep .NET 8 LTS builds for adapters/SDKs; publish compatibility matrix and upgrade runbooks.
NHibernate expertise	Ramp-up for teams newer to NH	Template samples, cookbook of mappings, “NH in ECS” guide; internal office hours.
Dual-bus complexity	Ops overhead	Clear ownership: lifecycle on ASB, refresh on Kafka; unified MassTransit instrumentation; chaos drills.
Redis memory pressure	Cache evictions → miss spikes	Snapshot size budgets, compression, shard by tenant, eviction SLO alerts.

ADRs to Record¶

ADR‑001: Adopt .NET 9 for core; maintain .NET 8 LTS compatibility for adapters/SDKs.
ADR‑002: Prefer NHibernate in core; allow EF Core in adapters.
ADR‑003: MassTransit as the messaging abstraction; ASB for lifecycle, Kafka/EH for refresh.
ADR‑004: Redis as the authoritative cache for snapshots; DB as source of truth.
ADR‑005: Enforce OpenTelemetry as mandatory for all services and adapters.

Ready-to-Implement Checklist¶

Bootstrap repos from ConnectSoft Microservice Template with CI/CD scaffolding.
Wire OTEL exporters and baseline dashboards (API, resolver, fanout, cache).
Provision CockroachDB/SQL, Redis, ASB/Kafka, and secrets stores with IaC.
Enable mTLS service mesh policies; gateway ETag and response caching.
Generate SDKs (.NET/JS) with versioned contracts and ETag semantics.
Publish ADRs and compatibility matrix; start perf baselines.

Strategic Technology Roadmap¶

The External Configuration System (ECS) must evolve alongside ConnectSoft’s broader SaaS ecosystem and technology principles. The roadmap is structured into near-term, mid-term, and long-term phases, ensuring ECS stays aligned with modern SaaS needs, scalable patterns, and AI-driven innovation.

📍 Near-Term (0–12 months)¶

Goals:

Deliver ECS MVP and core SaaS readiness.
Provide immediate value for ConnectSoft products needing centralized configuration.

Key Milestones:

✅ Multi-tenant ECS microservice with REST/gRPC APIs.
✅ ConnectSoft SDK integration (.NET, JavaScript).
✅ Versioning, rollback, and history APIs.
✅ Event-driven refresh using MassTransit + Azure Service Bus.
✅ Basic caching (Redis-backed).
✅ Config Studio v1: self-service UI portal for tenants.

📍 Mid-Term (12–24 months)¶

Goals:

Expand ECS capabilities into enterprise-grade SaaS.
Enhance cross-tenant, cross-context federation.

Key Milestones:

🟦 Support for federated ECS clusters across geographies.
🟦 Mesh-style configuration distribution using DDD context maps.
🟦 Fine-grained RBAC and edition overrides.
🟦 Advanced observability: OpenTelemetry traces for config refresh and API calls.
🟦 External integrations:
- Azure AppConfig
- AWS AppConfig
- HashiCorp Vault for secret-backed config.
🟦 Studio analytics dashboards (tenant usage, SLA tracking).

📍 Long-Term (24+ months)¶

Goals:

Position ECS as an intelligent, AI-driven configuration hub.
Extend ECS to support federated, cross-ecosystem SaaS architectures.

Key Milestones:

🌐 Global config federation with policy-aware routing.
🤖 AI-driven optimization: automatic detection of stale configs, anomaly detection, and proactive rollback.
🧪 Integration of feature flags + A/B testing natively into ECS.
🧩 Multi-cloud mesh distribution across Azure, AWS, and GCP.
📊 Predictive scaling: ECS scales config distribution clusters based on usage signals.
🛡 Continuous compliance scanning (SOC2, GDPR, HIPAA, industry extensions).

📊 Strategic Evolution Path¶

timeline
  title ECS Technology Roadmap
  section Near-Term
    ECS Microservice + SDKs : 2025 Q1
    Config Studio v1 : 2025 Q2
    Event-driven refresh : 2025 Q2
  section Mid-Term
    Federation & Mesh Support : 2026 Q1
    Enterprise Integrations (Azure/AWS) : 2026 Q2
    Advanced Observability : 2026 Q3
  section Long-Term
    AI-driven Config Optimization : 2027 Q1
    Config + Feature Flags + A/B Testing : 2027 Q2
    Multi-Cloud Federation : 2027 Q3

Hold "Alt" / "Option" to enable pan & zoom

✅ This roadmap ensures ECS is not only a core ConnectSoft utility but also a strategic SaaS product—starting with baseline SaaS value (MVP), extending to enterprise-grade federation, and evolving toward AI-driven innovation.

Cross‑Cutting Concerns¶

This section codifies platform‑wide policies and patterns that apply to every ECS service: schema validation, secrets handling, API compatibility, and feature toggle governance. These concerns are enforced through code templates, CI policies, and runtime guards.

Config Schema Validation & Contract Governance¶

Objectives

Prevent invalid or unsafe configs from reaching runtime.
Guarantee type safety, backward compatibility, and predictable resolution.

Standards

Schema format: JSON Schema 2020‑12 (primary).
Policy linting: rule bundles executed pre‑publish (range, regex, enums, cross‑field).
Compatibility: semantic contract rules (Additive ✅ / Deprecating ⚠ / Breaking ❌).

Validation Pipeline

flowchart LR
  Draft[Draft Config] --> Lint[Schema Lint + Policy Checks]
  Lint -->|OK| Compat[Compatibility Analyzer (B/C, additive?)]
  Compat -->|OK| Approvals[SoD Approvals (if required)]
  Approvals --> Sign[Sign & Version]
  Sign --> Publish[Publish + Snapshot Build]
  Lint -->|Fail| Feedback[Errors to Author]
  Compat -->|Fail| Feedback

Hold "Alt" / "Option" to enable pan & zoom

Schema Guidance

Use namespaced keys (payments.retry.max:int), enforce type + constraints.
Mark required, default, and nullable explicitly; avoid implicit defaults.
Sensitive classification via "x-classification": "secret|pii|internal".
Document resolution precedence (global < edition < tenant < env < app) in schema annotations.

Example (excerpt)

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "schemas/payments.json",
  "title": "Payments",
  "type": "object",
  "properties": {
    "payments.retry.max": { "type": "integer", "minimum": 0, "maximum": 10, "default": 3 },
    "payments.gateway":  { "type": "string", "enum": ["stripe","adyen","braintree"] },
    "db.conn":           { "type": "string", "pattern": "^@secret:.+" , "x-classification":"secret" }
  },
  "required": ["payments.gateway"]
}

Enterprise Architect Notes

Contracts are source‑controlled; changes require ADR + approval gate.
Every publish stores the exact schema hash with the version for reproducibility.

Secrets Handling (Never store secrets as values)¶

Objectives

Ensure secrets are never persisted in ECS data stores.
Provide indirection and auditable access via a Secrets Broker.

Pattern

Values are references (e.g., @secret:kv://tenant-123/prod/db).
Secrets are stored and rotated in Key Vault / Secrets Manager, resolved at consumer side or via broker.

Secret Resolution Flow

sequenceDiagram
  participant App as Service/SDK
  participant ECS as ECS API
  participant SB as Secrets Broker
  participant KV as Key Vault/KMS

  App->>ECS: GET config (needs db.conn)
  ECS-->>App: config payload (with @secret ref + signature)
  App->>SB: Resolve(@secret:kv://tenant-123/prod/db)
  SB->>KV: Fetch secret (policy + mTLS)
  KV-->>SB: Secret value
  SB-->>App: Short-lived handle/value (TTL)

Hold "Alt" / "Option" to enable pan & zoom

Controls

Per‑tenant KMS keys, mTLS between broker and vault, no logging of values, redaction at sinks.
Short‑lived handles (seconds‑minutes) with audited access; cache on client kept encrypted in memory.
Policy blocks: plain text when "x-classification": "secret".

Enterprise Architect Notes

Provide dry‑run mode in Studio to validate secret references without revealing values.

API Compatibility & Versioning (REST/gRPC/events)¶

Objectives

Evolve APIs without breaking tenants or SDKs.
Provide predictable deprecation windows and contract tests.

Policies

Versioning: URI (/v1/...), gRPC package versioning, and CloudEvents eventType with version.
Change classes:
- Additive (fields optional) → allowed in minors.
- Behavioral (default changes) → requires feature flag.
- Breaking → major only, with deprecation schedule.
Deprecation: announce T‑180/T‑90/T‑30 with headers: Sunset, Deprecation, Link.
Idempotency: Idempotency-Key required for publish/rollback.
Conditional: ETag/If-None-Match for reads; strong validators on payloads.

Evolution Model

flowchart TB
  Contracts[OpenAPI/Proto Contracts] --> CDC[Consumer-driven Contract Tests]
  CDC --> Gate[CI Policy Gate]
  Gate --> Release[Publish SDKs & API]
  Release --> Sunset[Deprecation Timeline]

Hold "Alt" / "Option" to enable pan & zoom

Enterprise Architect Notes

Maintain a version matrix (API ↔ SDKs) and enforce in CI.
Use CDC (Pact or equivalent) for critical integrators.

Feature Toggles & Progressive Delivery¶

Objectives

Decouple feature exposure from deployment.
Allow safe, staged rollout with kill‑switch support.

Model

Toggles live next to configs but are semantically distinct (FeatureFlag entity).
OpenFeature‑compatible evaluation on server/SDK; targeting by tenant/edition/env/user attributes.
Rollout strategies: ring/canary/percentage, time windows, constraints (e.g., region).

Control Flow

flowchart LR
  Flag[FeatureFlag] --> Rules[Targeting Rules]
  Rules --> Cohorts[Audience/Cohorts]
  Cohorts --> Signals[Refresh/Event Signals]
  Signals --> SDK[SDK Eval & Caching]

Hold "Alt" / "Option" to enable pan & zoom

Governance

Toggles must reference a backed feature spec (owner, risk class, rollback plan).
Kill‑switch is mandatory for high‑risk flags; evaluated client‑side and server‑side.
Telemetry: exposure, conversion (if defined), error correlation.

Example (YAML)

feature: premium.analytics.dashboard
state: on
strategies:
  - name: ramp
    percentage: 10
    audience: edition == "enterprise"
  - name: cohort
    includeTenants: ["acme","globex"]
killSwitch: true
observability:
  metrics:
    - exposure
    - error_rate

Cross‑Cutting Checks in CI/CD¶

Schema checks: JSON Schema compile + unit fixtures + migrations diff.
Policy pack: prohibited values, ranges, regexes, secret classification, PII guard.
API contract: OpenAPI/proto lint + backward‑compat checker + CDC.
Security: dependency scanning, SBOM, container scan, secrets detection (pre‑commit).
Observability: OTEL presence check, log redaction rules, metric cardinality budgets.

Runtime Guards¶

Admission controllers deny publishes missing policy permit or approvals.
Rate limits per tenant for publish/refresh; backoff hints on 429.
Read path requires scope‑aware tokens; tenantId claim enforced end‑to‑end.
Fail‑safe: on policy or schema failure → reject write; on read overload → serve signed LKG with stale=true.

Deliverables & Templates¶

Schema Registry service + CLI (validate, diff, promote, rollback).
Policy bundles (JSON/YAML) with unit tests and golden fixtures.
OpenAPI/Proto in dedicated repos with SDK generators (.NET/JS).
Feature Flag DSL (OpenFeature‑compatible) + evaluation library in SDKs.
Secrets Broker interface + adapters (Key Vault/Secrets Manager) with test doubles.

ADRs to Record¶

ADR‑010: JSON Schema 2020‑12 as canonical format for config contracts; policy lint mandatory pre‑publish.
ADR‑011: Secrets by reference only (@secret:); resolution via broker; no plaintext persistence/logging.
ADR‑012: API versioning policy (URI/grpc/events) with breaking‑change discipline and deprecation headers.
ADR‑013: Feature flags integrated but distinct from configs; OpenFeature‑compatible targeting and mandatory kill‑switch for risk‑class A features.

Readiness Checklist¶

Schema registry live; compatibility gates wired to CI.
Policy pack loaded; approvals flow active for risk‑class changes.
Deprecation headers enabled; version matrix published.
Feature flag service + SDK evaluation paths tested; kill‑switch verified.
Secrets Broker integrated; audit of secret access in place; redaction filters active.

Enterprise Architect Notes

Treat these concerns as product guardrails: they reduce incident surface, speed safe change, and protect tenant trust. All new services and adapters must pass the cross‑cutting gate before promotion.

Governance & Compliance Checklists¶

Governance and compliance are critical to ensure the External Configuration System (ECS) is not only technically sound but also aligned with enterprise-grade standards. This section formalizes the Enterprise Architecture (EA) compliance gates, the Definition of Ready (DoR) and Definition of Done (DoD) for ECS artifacts, and the review artifacts required at each lifecycle stage.

EA Compliance Gates¶

Each ECS artifact (vision, blueprint, microservice, library, portal) must pass compliance gates defined at enterprise level:

Gate	Criteria	Review Mechanisms
Architecture Compliance	Alignment to Clean Architecture, DDD, event-driven, cloud-native	Architecture review board, static analyzers
Security Compliance	RBAC, tenant isolation, no secrets leakage, encryption in transit/at rest	Automated security scans, OpenIddict/OAuth2 validation
Observability Compliance	Logs, traces, metrics aligned to OTEL; tenant-level visibility	Observability-driven design checks, Grafana dashboards
Performance Compliance	Meets SLA/QPS thresholds, passes load tests	Load/chaos testing agents, CI/CD gates
Compliance-by-Design	SOC2/GDPR readiness; audit logging	Audit trail validators, governance review
Template Alignment	Generated services conform to ConnectSoft templates	Template linter, generator validation

Definition of Ready (DoR)¶

An ECS backlog item (story, epic, feature) is ready when:

✅ Business value and acceptance criteria are clearly defined.
✅ Architecture context (bounded context, integration needs) is mapped.
✅ Dependencies (templates, libraries, events) are identified.
✅ Security and compliance requirements are annotated.
✅ Test strategy (unit/BDD, load) is outlined.

Definition of Done (DoD)¶

An ECS artifact is done when:

✅ Code and configs are generated from ConnectSoft templates.
✅ All tests (unit, BDD, integration) pass across editions and tenants.
✅ Observability hooks (logging, tracing, metrics) are embedded.
✅ Compliance scans (secrets, PII, policy) return clean results.
✅ Documentation (README, ADR, API contracts) is generated and linked to knowledge/memory system.
✅ Governance review signed off (automated + manual).

Architecture Review Artifacts¶

To support compliance and governance, the following review artifacts must be produced and stored in memory:

Architecture Decision Records (ADR) – rationale for design decisions.
Traceability Matrix – feature → requirement → service → test mapping.
Event Catalog – ECS events, schemas, consumers.
Context & Data Models – domain-driven decomposition, ERDs.
Compliance Checklist – per service, validated at CI/CD gates.
Audit Evidence – logs, scans, observability traces per release.

flowchart TD
   A[Feature Request] --> B[Definition of Ready]
   B --> C[Implementation via Templates]
   C --> D[Compliance Gates]
   D --> E[Definition of Done]
   E --> F[Release & Audit Evidence]

Hold "Alt" / "Option" to enable pan & zoom

✅ Enterprise Architect Perspective: Governance and compliance are not afterthoughts—they are designed into ECS templates, microservices, and libraries. Every artifact must be ready, compliant, and observable before being marked done.

ECS System Architecture Blueprint (SAB)¶

Enterprise Architecture Objectives¶

🎯 Role of the Enterprise Architect for ECS¶

🏆 Key Architecture Drivers¶

1. Scalability¶

2. Compliance¶

3. SaaS Readiness¶

📐 EA Objective Diagram¶

📌 Enterprise Architect Notes¶

Business–Technology Alignment¶

🎯 Alignment with Business Objectives¶

📊 Translating Business KPIs to Architecture KPIs¶

🔗 EA Role in Business–Tech Alignment¶

📐 Alignment Diagram¶

📌 Enterprise Architect Notes¶

Context & Scope Definition¶

🌍 ECS in the ConnectSoft Ecosystem¶

✅ In-Scope¶

🚫 Out-of-Scope¶

📐 ECS Context Diagram¶

📌 Enterprise Architect Notes¶

Architecture Principles¶

🧩 Core Principles¶

📐 Principle Map¶

📌 Enterprise Architect Notes¶

High‑Level System Blueprint¶

Core Components & Boundaries¶

Runtime Flows (Read Path & Change Propagation)¶

Microservices & Responsibilities¶

Data & Storage View¶

External & Ecosystem Integrations¶

Trust Zones & Network¶

Deployment Topology (Cloud‑Native)¶

Non‑Functional Guardrails (at Blueprint Level)¶

Domain Decomposition & Bounded Contexts (DDD)¶

Context Map (Strategic Design)¶

Contexts → Capabilities → Primary Aggregates¶

Ubiquitous Language (Core Terms)¶

Aggregate Design (Tactical DDD)¶

Config Authoring¶

Serving & Resolution¶

Tenancy & Editions¶

Policy & Governance¶

Refresh & Distribution¶

Integrations¶

Observability & Audit¶

Billing¶

Domain Event Catalog (Inter‑Context Contracts)¶

Context Integration Styles¶

Resolution Precedence Model¶

Data Ownership & Isolation¶

Example Command & Event (Intent‑first)¶

Anti‑Corruption Layers (Integrations)¶

Guardrails (Cross‑Cutting)¶

Outcome¶

Service Decomposition & Responsibilities¶

Service Inventory (by responsibility)¶

Responsibility Breakdown (concise RASCI)¶

Change Flows (Write Path)¶

Read Flows (Hot Path / 99th percentile)¶

Event Contract Highlights (selected)¶

Data Ownership & Boundaries¶

Failure & Resiliency Responsibilities¶

Service-to-Template Mapping (ConnectSoft assets)¶

Responsibility Guardrails (policy snippets)¶

Open Questions to Close (for subsequent cycles)¶

Data Architecture & Lifecycle¶

Entity-Relationship Model (ERD)¶

Data Lineage & Lifecycle¶

Retention & Compliance¶

Partitioning Strategy¶

Data Flow Observability¶

Enterprise Architect Notes¶

Integration Architecture — External Configuration System (ECS)¶

Integration Goals¶

High-Level Integration Map¶

Core Integration Patterns¶

1) Identity & Access (ConnectSoft IdP)¶

2) Tenant, Edition, and Billing Hooks¶

3) Event-Driven Refresh & Rollout¶

Read Flows (Hot Path / 99^th percentile)¶